Marine debris and human impacts on sea turtles in southern Brazil

Energy Technology Data Exchange (ETDEWEB)

Bugoni, Leandro; Krause, Ligia [Universidade Federal do Rio Grande do Sul, Dept. de Zoologia, Porto Alegre, RS (Brazil); Petry, Maria Virginia [Universidade do Rio dos Sinos, Museu de Zoologia, Sao Leopoldo, RS (Brazil)

2001-07-01

Dead stranded sea turtles were recovered and examined to determine the impact of anthropogenic debris and fishery activities on sea turtles on the coast of Rio Grande do Sul State, Brazil. Esophagus/stomach contents of 38 juvenile green Chelonia mydas, 10 adults and sub-adults loggerhead Caretta caretta, and two leatherback Dermochelys coriacea turtle (adult or sub-adult) included plastic bags as the main debris ingested, predominated by white and colorless pieces. The ingestion of anthropogenic debris accounted for the death of 13.2% of the green turtles examined. Signs of damage over the body and carapace indicated that fishing activities caused the death of 13.6% (3/22) of loggerheads and 1.5% (1/56) of green turtles. Therefore, it appears that direct and indirect effects of fishing activities may pose a threat to these species in Brazilian waters. Other sources of plastic debris should be investigated as well a the direct impact of fisheries, especially bottom trawl and gill nets, in order to establish effective conservation action. (Author)

Space Transportation System Liftoff Debris Mitigation Process Overview

Science.gov (United States)

Mitchell, Michael; Riley, Christopher

2011-01-01

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

DRAGONS-A Micrometeoroid and Orbital Debris Impact Sensor on the ISS

Science.gov (United States)

Liou, J.-C.; Hamilton, J.; Liolios, S.; Anderson, C.; Sadilek, A.; Corsaro, R.; Giovane, F.; Burchell, M.

2015-01-01

The Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is intended to be a large area impact sensor for in situ measurements of micrometeoroids and orbital debris (MMOD) in the sub-millimeter to millimeter size regime in the near Earth space environment. These MMOD particles are too small to be detected by ground-based radars and optical telescopes, but still large enough to be a serious threat to human space activities and robotic missions in the low Earth orbit (LEO) region. The nominal detection area of DRAGONS is 1 sq m, consisting of four 0.5 m × 0.5 m independent panels, but the dimensions of the panels can easily be modified to accommodate different payload constraints. The approach of the DRAGONS design is to combine three particle impact detection concepts to maximize information that can be extracted from each detected impact. The first is a resistive grid consisting of 75-micrometer-wide resistive lines, coated in parallel and separated by 75 micrometer gaps on a 25-micrometer thin film. When a particle a few hundred micrometers or larger strikes the grid, it would penetrate the film and sever some resistive lines. The size of the damage area can be estimated from the increased resistance. The second concept is based on polyvinylidene fluoride (PVDF) acoustic impact sensors. Multiple PVDF sensors are attached to the thin film to provide the impact timing information. From the different signal arrival times at different acoustic sensors, the impact location can be calculated via triangulation algorithms. The third concept employs a dual-layer film system where a second 25-micrometer film is placed 15 cm behind the resistive-grid film. Multiple PVDF acoustic sensors are also attached to the second film. The combination of impact timing and location information from the two films allows for direct measurements of the impact direction and speed. The DRAGONS technology development has been funded by several NASA organizations since 2002, first

Analysis of Damage in Laminated Architectural Glazing Subjected to Wind Loading and Windborne Debris Impact

Directory of Open Access Journals (Sweden)

Daniel S. Stutts

2013-05-01

Full Text Available Wind loading and windborne debris (missile impact are the two primary mechanisms that result in window glazing damage during hurricanes. Wind-borne debris is categorized into two types: small hard missiles; such as roof gravel; and large soft missiles representing lumber from wood-framed buildings. Laminated architectural glazing (LAG may be used in buildings where impact resistance is needed. The glass plies in LAG undergo internal damage before total failure. The bulk of the published work on this topic either deals with the stress and dynamic analyses of undamaged LAG or the total failure of LAG. The pre-failure damage response of LAG due to the combination of wind loading and windborne debris impact is studied. A continuum damage mechanics (CDM based constitutive model is developed and implemented via an axisymmetric finite element code to study the failure and damage behavior of laminated architectural glazing subjected to combined loading of wind and windborne debris impact. The effect of geometric and material properties on the damage pattern is studied parametrically.

Mixed debris treatment at the Idaho National Engineering Laboratory (INEL)

International Nuclear Information System (INIS)

Garcia, E.C.; Porter, C.L.; Wallace, M.T.

1993-01-01

August 18, 1992 the EPA published the final revised treatment standards for hazardous debris, including mixed debris. Whereas previous standards had been concentration based, the revised standards are performance based. Debris must be treated prior to land disposal, using specific technologies from one or more of the following families of debris treatment technologies: Extraction, destruction, or immobilization. Seventeen specific technologies with generic application are discussed in the final rule. The existing capabilities and types of debris at the INEL were evaluated against the debris rule to determine an overall treatment strategy for the INEL. Seven types of debris were identified: Combustible, porous, non-porous, inherently hazardous, HEPA filters, asbestos contaminated, and reactive metals contaminated debris. With the exception of debris contaminated with reactive metals treatment can be achieved utilizing existing facilities coupled with minor modifications

Mixed debris treatment at the Idaho National Engineering Laboratory (INEL)

International Nuclear Information System (INIS)

Garcia, E.C.; Porter, C.L.; Wallace, M.T.

1993-01-01

August 18, 1992 the Environmental Protection Agency (EPA) published the final revised treatment standards for hazardous debris, including mixed debris. (1) Whereas previous standards had been concentration based, the revised standards are performance based. Debris must be treated prior to land disposal, using specific technologies from one or more of the following families of debris treatment technologies: Extraction, destruction, or immobilization. Seventeen specific technologies with generic application are discussed in the final rule. The existing capabilities and types of debris at the INEL were scrubbed against the debris rule to determine an overall treatment strategy. Seven types of debris were identified: combustible, porous, non-porous, inherently hazardous, HEPA filters, asbestos contaminated, and reactive metals contaminated debris. With the exception of debris contaminated with reactive metals treatment can be achieved utilizing existing facilities coupled with minor modifications

Energy balance, carbon emissions, and costs of sortyard debris disposal

International Nuclear Information System (INIS)

MacDonald, A.J.

2001-01-01

The Forest Engineering Research Institute of Canada (FERIC), with funding from Natural Resources Canada, conducted this study to determine the main environmental and energy use issues regarding the landfilling, burning or processing of dryland sortyard debris accumulated in the wood products industry. The wood residues that are generated when logs are processed, sorted and remanufactured, have traditionally been burned or landfilled. This is no longer appropriate. Converting the large woody debris into usable products such as hog fuel or compost requires grinding, smashing or chipping into small pieces to facilitate transportation. In order to make smart decisions about alternative methods of handling sortyard debris, information is needed about the comparative amount of fuel used and carbon dioxide produced. This study compared the treatment alternatives with respect to fuel consumption, net energy balance, carbon dioxide emissions and environmental impact. Recommendations were then presented for the treatment of debris from the point of view of net energy balance and environmental impact. Life cycle techniques were used to determine the environmental impact of alternatives for managing sortyard debris. It was determined that wood wastes are valuable as hog fuel for power generation. Burning hog fuel to recover its energy offsets the need to supply energy from other sources such as natural gas. This reduces the total carbon emissions by the amount of debris that would have been burned as waste. Annual carbon emissions can be reduced by nearly half by switching from a maximize burn strategy to a maximize hog strategy that combines composting of fine materials. 2 refs., 1 tab., 1 fig

Impacts of weathered tire debris on the development of Rana sylvatica larvae.

Science.gov (United States)

Camponelli, Kimberly M; Casey, Ryan E; Snodgrass, Joel W; Lev, Steven M; Landa, Edward R

2009-02-01

Highway runoff has the potential to negatively impact receiving systems including stormwater retention ponds where highway particulate matter can accumulate following runoff events. Tire wear particles, which contain about 1% Zn by mass, make up approximately one-third of the vehicle derived particulates in highway runoff and therefore may serve as a stressor to organisms utilizing retention ponds as habitat. In this study, we focused on the potential contribution of tire debris to Zn accumulation by Rana sylvatica larvae and possible lethal or sublethal impacts resulting from exposure to weathered tire debris during development. Eggs and larvae were exposed to aged sediments (containing either ZnCl2 or tire particulate matter, both providing nominal concentrations of 1000 mg Zn kg(-1)) through metamorphosis. Water column Zn was elevated in both the ZnCl2 and tire treatments relative to the control treatment, indicating that aging allowed Zn leaching from tire debris to occur. Tissue Zn was also elevated for the ZnCl2 and tire treatments indicating that Zn in the treatments was available for uptake by the amphibians. Exposure to both ZnCl2 and tire treatments increased the time for larvae to complete metamorphosis in comparison with controls. We also observed that the longer the organisms took to complete metamorphosis, the smaller their mass at metamorphosis. Our results indicate that Zn leached from aged tire debris is bioavailable to developing R. sylvatica larvae and that exposure to tire debris amended sediments can result in measurable physiological outcomes to wood frogs that may influence population dynamics.

Impacts of weathered tire debris on the development of Rana sylvatica larvae

Science.gov (United States)

Camponelli, K.M.; Casey, R.E.; Snodgrass, J.W.; Lev, S.M.; Landa, E.R.

2009-01-01

Highway runoff has the potential to negatively impact receiving systems including stormwater retention ponds where highway particulate matter can accumulate following runoff events. Tire wear particles, which contain about 1% Zn by mass, make up approximately one-third of the vehicle derived particulates in highway runoff and therefore may serve as a stressor to organisms utilizing retention ponds as habitat. In this study, we focused on the potential contribution of tire debris to Zn accumulation by Rana sylvatica larvae and possible lethal or sublethal impacts resulting from exposure to weathered tire debris during development. Eggs and larvae were exposed to aged sediments (containing either ZnCl2 or tire particulate matter, both providing nominal concentrations of 1000 mg Zn kg-1) through metamorphosis. Water column Zn was elevated in both the ZnCl2 and tire treatments relative to the control treatment, indicating that aging allowed Zn leaching from tire debris to occur. Tissue Zn was also elevated for the ZnCl2 and tire treatments indicating that Zn in the treatments was available for uptake by the amphibians. Exposure to both ZnCl2 and tire treatments increased the time for larvae to complete metamorphosis in comparison with controls. We also observed that the longer the organisms took to complete metamorphosis, the smaller their mass at metamorphosis. Our results indicate that Zn leached from aged tire debris is bioavailable to developing R. sylvatica larvae and that exposure to tire debris amended sediments can result in measurable physiological outcomes to wood frogs that may influence population dynamics. ?? 2008 Elsevier Ltd.

DRAGONS - A Micrometeoroid and Orbital Debris Impact Sensor

Science.gov (United States)

Liou, J. -C.; Corsaro, R.; Giovane, F.; Anderson, C.; Sadilek, A.; Burchell, M.; Hamilton, J.

2015-01-01

The Debris Resistive/Acoustic Grid Orbital Navy-NASA Sensor (DRAGONS) is intended to be a large area impact sensor for in situ measurements of micrometeoroids and orbital debris (MMOD) in the millimeter or smaller size regime. These MMOD particles are too small to be detected by ground-based radars and optical telescopes, but are still large enough to be a serious safety concern for human space activities and robotic missions in the low Earth orbit (LEO) region. The nominal detection area of a DRAGONS unit is 1 m2, consisting of several independently operated panels. The approach of the DRAGONS design is to combine different particle impact detection principles to maximize information that can be extracted from detected events. After more than 10 years of concept and technology development, a 1 m2 DRAGONS system has been selected for deployment on the International Space Station (ISS) in August 2016. The project team achieved a major milestone when the Preliminary Design Review (PDR) was completed in May 2015. Once deployed on the ISS, this multi-year mission will provide a unique opportunity to demonstrate the MMOD detection capability of the DRAGONS technologies and to collect data to better define the small MMOD environment at the ISS altitude.

ORDEM2010 and MASTER-2009 Modeled Small Debris Population Comparison

Science.gov (United States)

Krisko, Paula H.; Flegel, S.

2010-01-01

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

Local behavior of reinforced concrete slabs to aircraft engine projectile impact

International Nuclear Information System (INIS)

Yoo, Hyeon Kyeong; Choi, Hyun; Chung, Chul Hun; Lee, Jung Whee; Kim, Sang Yun

2011-01-01

Structural safety evaluation of nuclear power plant considers two distinct types of structural failure, local failure and global failure. In the local failure evaluation, considered projectiles can be divided as internal and external projectile according to the impact location, and they also can be divided as rigid and soft projectile according to the deformation level after impact. Frequently considered projectiles are aircraft engine, tornado, and turbine projectile. When the speed and weight of the projectiles are considered, the most influential projectile is aircraft engine, which is one of the soft projectiles. Sugano et al. performed impact test using an engine model projectile, which is derived from GE-J79 engine and concentrated mass-spring model idealization. Kojima and Sugano et al. demonstrated from their experiments that steel liner on the rear side of the concrete wall reduces impact induced damage and suppresses debris scattering. Chung et al. performed comparison study of various formulae suggested for local damage evaluation using previously performed numerous local impact test results. Also, they validated a methodology of numerical analysis for impact simulation using LS-DYNA. Previously suggested formulae and research results do not consider the effect of liner plate or curved shape of the containment building walls on the local damage. In this research, flat wall and curved wall are individually modeled using the same curvature of nuclear power plants, and the effects of curvature and liner plates on the local damage are analytically investigated

The impact of debris on the Florida manatee

Science.gov (United States)

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.

Active Debris Removal and the Challenges for Environment Remediation

Science.gov (United States)

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.

Marine debris: global and regional impacts

OpenAIRE

Torres N,Daniel; Berguño B,Jorge

2011-01-01

A synthesis on the Marine Debris problem is given upon de basis of the general knowledge on the matter as well as that obtained at Cape Shirreff, Livingston Island, South Shetland, Antarctica. It is suggested to improve the database on marine debris through permanent scientific research as well as with monitoring activities. It is necessary to coordinate key groups to apply strategies to identify types, sources, amount, interactions and socio-economic aspects of this global and regional probl...

DebriSat: The New Hypervelocity Impact Test for Satellite Breakup Fragment Characterization

Science.gov (United States)

Cowardin, Heather

2015-01-01

To replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoD and NASA breakup models: DebriSat is intended to be representative of modern LEO satellites. Major design decisions were reviewed and approved by Aerospace subject matter experts from different disciplines. DebriSat includes 7 major subsystems. Attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. center dotA key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), supporting the development of the DoD and NASA satellite breakup models was conducted at AEDC in 1992. Breakup models based on SOCIT have supported many applications and matched on-orbit events reasonably well over the years.

DebriSat Project Update and Planning

Science.gov (United States)

Sorge, M.; Krisko, P. H.

2016-01-01

DebriSat Reporting Topics: DebriSat Fragment Analysis Calendar; Near-term Fragment Extraction Strategy; Fragment Characterization and Database; HVI (High-Velocity Impact) Considerations; Requirements Document.

[Research progress in post-fire debris flow].

Science.gov (United States)

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.

ORDEM 3.0 and MASTER-2009 Modeled Small Debris Population Comparison

Science.gov (United States)

Krisko, P. H.; Flegel, S.

2014-01-01

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

Debris impact on emergency coolant recirculation - summary and conclusions

International Nuclear Information System (INIS)

Jain, Bhagwat; Hsia, Anthony; Armand, Yves; Mattei, Jean-Marie; Hyvaerinen, Juhani; Maqua, Michael; Puetter, Bernhard; Sandervaag, Oddbjoern; Vandewalle, Andre; Tombuyses, Beatrice; Pyy, Pekka; Royen, Jacques

2004-01-01

to two orders of magnitude because of strainer clogging. Consequently, the CSNI decided to continue its previous efforts in the area. The overall purpose of the 2004 Workshop was to discuss the impact of new information made available since 1996 and to promote consensus among member countries on identification of remaining technical issues important to safety, and on possible paths for their resolution. The specific purposes of the Workshop were: a. To review the knowledge base and in particular information developed after 1999, and to consider the validity of the conclusions drawn. b. To exchange information on the current status of research related to debris generation, debris transportation, and sump strainer clogging and penetration phenomena, in particular for PWRs, and to assess uncertainties. c. To exchange and disseminate information on recent and current activities and practices in these areas. d. To identify and discuss differences between approaches relevant to reactor safety. e. To identify technical issues and programs of interest for international collaborative research and develop an Action Plan outlining activities that CSNI should undertake in the area of strainer or sump screen clogging during the next few years. Summary of the main findings: a. The safety significance of the sump strainer clogging depends on the plant design (e.g. sump strainer, ECCS) and backfitting measures performed. b. The following are examples of PWR design features that could influence the debris impact on the ECCS sump performance: - Type of insulation (material, combination of materials, protection). - Break size to be postulated. - Transport in containment with or without containment spray system (CSS). - Degree of turbulence and flow velocities in the sump influenced by CSS, water level, break flow location and sump geometry. - Redundancy of sumps and residual heat removal system (RHRS). - Strainer design (area, mesh size). - Positioning of recirculation pumps and vortex

Mechanical properties of glasses impacted by debris or micrometeorites

Science.gov (United States)

Kinser, Donald L.; Wiedlocher, David E.

1992-01-01

Mechanical strength measurements on five glasses and one glass ceramic exposed on the Long Duration Exposure Facility (LDEF) have revealed no damage exceeding experimental limits of error after exposure. The measurement technique subjected less than 5 percent of the sample surface area to stresses above 90 percent of the failure strength. Seven micrometeorite or space debris impacts occurred at locations which were not in that portion of the sample subjected to greater than 90 percent of the applied stress. In consequence of this, the impact events on the sample were not detected in mechanical strength measurements. The physical form and structure of the impact sites was carefully examined to determine the influence of those events upon stress concentration associated with the impact and the resulting mechanical strength influence. The size of the impact site insofar as it determines flaw size for fracture purposes was examined. Surface topography of the impacts reveals that six of the seven sites display impact melting. The classical melt crater structure is surrounded by a zone of fractured glass. Residual stresses arising from shock compression and from cooling of the impact fused zone cannot be included in fracture mechanics analyses based on simple flaw size analyses. Strategies for refining estimates of mechanical strength degradation by impact events are presented.

Debris thickness patterns on debris-covered glaciers

Science.gov (United States)

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.

Electron microscope observations of impact crater debris amongst contaminating particulates on materials surfaces exposed in space in low-Earth orbit

Science.gov (United States)

Murr, L. E.; Rivas, J. M.; Quinones, S.; Niou, C.-S.; Advani, A. H.; Marquez, B.

1993-01-01

Debris particles extracted from a small sampling region on the leading edge of the Long Duration Exposure Facility (LDEF) spacecraft have been examined by analytical transmission electron microscopy and the elemental frequency observed by energy-dispersive X-ray spectrometry and compared with upper atmosphere (Earth) particle elemental frequency and the average elemental compositions of interplanetary dust particles. A much broader elemental distribution was observed for the exposed spacecraft surface debris milieu. Numerous metal microfragment analyses, particularly aluminum and stainless steel, were compared with scanning electron microscope observations-of impact crater features, and the corresponding elemental spectra on selected LDEF aluminium tray clamps and stainless steel bolts. The compositions and melt features for these impact craters and ejecta have been shown to be consistent with microcrystalline debris fragments in the case of aluminum, and these observations suggest an ever changing debris milieu on exposed surfaces for space craft and space system materials.

TMI defueling project fuel debris removal system

International Nuclear Information System (INIS)

Burdge, B.

1992-01-01

The three mile Island Unit 2 (TMI-2) pressurized water reactor loss-of-coolant accident on March 28, 1979, presented the nuclear community with many challenging remediation problems; most importantly, the removal of the fission products within the reactor containment vessel. To meet this removal problem, an air-lift system (ALS) can be used to employ compressed air to produce the motive force for transporting debris. Debris is separated from the transport stream by gravity separation. The entire method does not rely on any moving parts. Full-scale testing of the ALS at the Idaho National Engineering Laboratory (INEL) has demonstrated the capability of transporting fuel debris from beneath the LCSA into a standard fuel debris bucket at a minimum rate of 230 kg/min

Algorithms for the Computation of Debris Risk

Science.gov (United States)

Matney, Mark J.

2017-01-01

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

A real two-phase submarine debris flow and tsunami

International Nuclear Information System (INIS)

Pudasaini, Shiva P.; Miller, Stephen A.

2012-01-01

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

A real two-phase submarine debris flow and tsunami

Energy Technology Data Exchange (ETDEWEB)

Pudasaini, Shiva P.; Miller, Stephen A. [Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn Nussallee 8, D-53115, Bonn (Germany)

2012-09-26

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

Uncertainty propagation for statistical impact prediction of space debris

Science.gov (United States)

Hoogendoorn, R.; Mooij, E.; Geul, J.

2018-01-01

Predictions of the impact time and location of space debris in a decaying trajectory are highly influenced by uncertainties. The traditional Monte Carlo (MC) method can be used to perform accurate statistical impact predictions, but requires a large computational effort. A method is investigated that directly propagates a Probability Density Function (PDF) in time, which has the potential to obtain more accurate results with less computational effort. The decaying trajectory of Delta-K rocket stages was used to test the methods using a six degrees-of-freedom state model. The PDF of the state of the body was propagated in time to obtain impact-time distributions. This Direct PDF Propagation (DPP) method results in a multi-dimensional scattered dataset of the PDF of the state, which is highly challenging to process. No accurate results could be obtained, because of the structure of the DPP data and the high dimensionality. Therefore, the DPP method is less suitable for practical uncontrolled entry problems and the traditional MC method remains superior. Additionally, the MC method was used with two improved uncertainty models to obtain impact-time distributions, which were validated using observations of true impacts. For one of the two uncertainty models, statistically more valid impact-time distributions were obtained than in previous research.

From orbital debris capture systems through internal combustion engines on Mars

Science.gov (United States)

1991-01-01

The investigation and conceptualization of an orbital debris collector was the primary area of design. In addition, an alternate structural design for Space Station Freedom and systems supporting resource utilization at Mars and the moon were studied. Hardware for production of oxygen from simulate Mars atmosphere was modified to permit more reliable operation at low pressures (down to 10 mb). An internal combustion engine was altered to study how Mars atmosphere could be used as a diluent to control combustion temperatures and avoid excess Mars propellant production requirements that would result from either methane-rich or oxygen-rich, methane-oxygen combustion. An elastic loop traction system that could be used for lunar construction vehicles was refined to permit testing. A parabolic heat rejection radiator system was designed and built to determine whether it was capable of increasing heat rejection rates during lunar daytime operation. In addition, an alternate space station truss design, utilizing a pre-integrated concept, was studied and found to reduce estimate extravehicular activity (EVA) time and increase the structural integrity when compared to the original Warren truss concept. An orbital-debris-capturing spacecraft design which could be mated with the Orbital Maneuvering Vehicle was studied. The design identified Soviet C-1B boosters as the best targets of opportunity in Earth orbits between an altitude of 900 km and 1100 km and at an inclination of 82.9 deg. A dual robot pallet, which could be spun to match the tumbling rate of the C-1B booster, was developed as the conceptual design.

Algorithms for the Computation of Debris Risks

Science.gov (United States)

Matney, Mark

2017-01-01

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

Characteristics of Large Low-frequency Debris Flow Hazards and Mitigation Strategies

Institute of Scientific and Technical Information of China (English)

WANG Shige

2005-01-01

A low-frequency debris flow took place in the north coastal range of Venezuela on Dec. 16, 1999,and scientists all over the world paid attention to this catastrophe. Four characteristics of low-frequency debris hazard are discussed: long return period and extreme catastrophe, special rare triggering factors,difficulty in distinguishing and a series of small hazards subsequent to the catastrophe. Different measures, such as preventing, forecast - warning,engineering, can be used for mitigating and controlling the catastrophe. In engineering practice, it is a key that large silt-trap dams are used to control rare large debris flow. A kind of low dam with cheap cost can be used to replace high dam in developing countries. A planning for controlling debris flow hazard in Cerro Grande stream of Venezuela is presented at the end of this paper.

Comparison of debris environment models (MASTER-2005, 2001, ORDEM2000): For international standardization of process based implementation of meteoroid and debris environmental models

OpenAIRE

Fukushige, Shinya; Akahoshi, Yasuhiro; Kitazawa, Yukihito; Goka, Tateo; 福重　進也; 赤星　保浩; 北澤　幸人; 五家　建夫

2007-01-01

Space agencies of some countries have space debris environment model for design of spacecrafts. These models can estimate debris flux as a function of the size, relative impact velocity, and impact angle in a spacecraft orbit. However, it is known calculation results of models are not always consistent with each other. Therefore, international common implementation process of debris environment model is required. In this paper, as the first step of international standardization of implementat...

Protecting Spacecraft Fragments from Exposure to Small Debris

Directory of Open Access Journals (Sweden)

V. V. Zelentsov

2015-01-01

less than 4 ... 5 km/s, at higher speeds particles breaks through them. As a result, a cloud is formed. It consists of fragments, destroying particle, and debris split-off from the obstacle. For reliable protection the sandwich panels are used. Shield design comprises two panels: the first panel being multi-layer and the second one being single-layer. The task of the first panel is to provide the maximum fragmented particle and reduce its speed. The second panel protects the structure from the cloud fragments resulting from breakdown of the first panel. The European module "Columbus” that is part of the ISS and transport vehicle ATV have the protective shield of the similar construction. The shield consists of "aluminum sheet with 2 mm thickness; filler - Kevlar + Nextel + epoxy resin, thermal insulation; the second panel comprises aluminum sheet of 3 mm thickness.Modeling and experiments show high efficiency of steel mesh as a protective shield. Spacecraft design consists, mainly, of aluminum alloys therefore space debris is from the same material. At collision with steel mesh a particle is decelerated and destroyed. Therefore, timeRushan ability of the particle significantly decreases. The second layer, opposing to the impact of high-speed particles, is foam metal (foam-Lumina. It is successfully used in the automotive engineering. Ballistic fabric (such as Kevlar is capable to protect from the effect of the fragmentation cloud.

Hydrogen sulfide generation in simulated construction and demolition debris landfills: impact of waste composition.

Science.gov (United States)

Yang, Kenton; Xu, Qiyong; Townsend, Timothy G; Chadik, Paul; Bitton, Gabriel; Booth, Matthew

2006-08-01

Hydrogen sulfide (H2S) generation in construction and demolition (C&D) debris landfills has been associated with the biodegradation of gypsum drywall. Laboratory research was conducted to observe H2S generation when drywall was codisposed with different C&D debris constituents. Two experiments were conducted using simulated landfill columns. Experiment 1 consisted of various combinations of drywall, wood, and concrete to determine the impact of different waste constituents and combinations on H2S generation. Experiment 2 was designed to examine the effect of concrete on H2S generation and migration. The results indicate that decaying drywall, even alone, leached enough sulfate ions and organic matter for sulfate-reducing bacteria (SRB) to generate large H2S concentrations as high as 63,000 ppmv. The codisposed wastes show some effect on H2S generation. At the end of experiment 1, the wood/drywall and drywall alone columns possessed H2S concentrations > 40,000 ppmv. Conversely, H2S concentrations were debris landfills are suggested.

ABB. CASE's GUARDIANTM Debris Resistant Fuel Assembly Design

International Nuclear Information System (INIS)

Dixon, D. J.; Wohlsen, W. D.

1992-01-01

ABB CE's experience, that 72% of all recent fuel-rod failures are caused by debris fretting, is typical. In response to this problem, ABB Combustion Engineering began supplying in the late 1980s fuel assemblies with a variety of debris resistant features, including both long-end caps and small flow holes. Now ABB CAE has developed an advanced debris resistant design concept, GUARDIAN TM , which has the advantage of capturing and retaining more debris than other designs, while displacing less plenum or active fuel volume than the long end-cap design. GUARDIAN TM design features have now been implemented into four different assembly designs. ABB CASE's GUARDIAN TM fuel assembly is an advanced debris-resistant design which has both superior filtering performance and uniquely, excellent debris retention, Retention effectively removes the debris from circulation in the coolant so that it is not able to threaten the fuel again. GUARDIAN TM features have been incorporated into four ABB. CAE fuel assembly designs. These assemblies are all fully compatible with the NSLS, and full-batch operation with GUARDIAN TM began in 1992. The number of plants of both CAE and non-CAE design which accept GUARDIAN TM for debris protection is expected to grow significantly during the next few years

Examination of returned solar-max surfaces for impacting orbital debris and meteoroids

Science.gov (United States)

Kessler, D. J.; Zook, H. A.; Potter, A. E.; Mckay, D. S.; Clanton, U. S.; Warren, J. L.; Watts, L. A.; Schultz, R. A.; Schramm, L. S.; Wentworth, S. J.

1985-01-01

Previous theoretical studies predicted that in certain regions of earth orbit, the man-made earth orbiting debris environment will soon exceed the interplanetary meteoroid environment for sizes smaller than 1 cm. The surfaces returned from the repaired Solar Max Mission (SMM) by STS 41-C on April 12, 1984, offered an excellent opportunity to examine both the debris and meteoroid environments. To date, approximately 0.7 sq. met. of the thermal insulation and 0.05 sq. met of the aluminum louvers have been mapped by optical microscope for crater diameters larger than 40 microns. Craters larger in diameter than about 100 microns found on the initial 75 micron thick Kapton first sheet on the MEB (Main Electronics Box) blanket are actually holes and constitute perforations through that blanket. The following populations have been found to date in impact sites on these blankets: (1) meteoritic material; (2) thermal paint particles; (3) aluminum droplets; and (4) waste particles.

Economic analysis requirements in support of orbital debris regulatory policy

Science.gov (United States)

Greenberg, Joel S.

1996-10-01

As the number of Earth orbiting objects increases so does the potential for generating orbital debris with the consequent increase in the likelihood of impacting and damaging operating satellites. Various debris remediation approaches are being considered that encompass both in-orbit and return-to-Earth schema and have varying degrees of operations, cost, international competitiveness, and safety implications. Because of the diversity of issues, concerns and long-term impacts, there is a clear need for the setting of government policies that will lead to an orderly abatement of the potential orbital debris hazards. These policies may require the establishment of a supportive regulatory regime. The Department of Transportation is likely to have regulatory responsibilities relating to orbital debris stemming from its charge to protect the public health and safety, safety of property, and national security interests and foreign policy interests of the United States. This paper describes DOT's potential regulatory role relating to orbital debris remediation, the myriad of issues concerning the need for establishing government policies relating to orbital debris remediation and their regulatory implications, the proposed technological solutions and their economic and safety implications. Particular emphasis is placed upon addressing cost-effectiveness and economic analyses as they relate to economic impact analysis in support of regulatory impact analysis.

POST Earthquake Debris Management - AN Overview

Science.gov (United States)

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

Monitoring the abundance of plastic debris in the marine environment

NARCIS (Netherlands)

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

2009-01-01

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

The complex interaction between marine debris and toxic chemicals in the ocean.

Science.gov (United States)

Engler, Richard E

2012-11-20

Marine debris, especially plastic debris, is widely recognized as a global environmental problem. There has been substantial research on the impacts of plastic marine debris, such as entanglement and ingestion. These impacts are largely due to the physical presence of plastic debris. In recent years there has been an increasing focus on the impacts of toxic chemicals as they relate to plastic debris. Some plastic debris acts as a source of toxic chemicals: substances that were added to the plastic during manufacturing leach from plastic debris. Plastic debris also acts as a sink for toxic chemicals. Plastic sorbs persistent, bioaccumulative, and toxic substances (PBTs), such as polychlorinated biphenyls (PCBs) and dioxins, from the water or sediment. These PBTs may desorb when the plastic is ingested by any of a variety of marine species. This broad look at the current research suggests that while there is significant uncertainty and complexity in the kinetics and thermodynamics of the interaction, plastic debris appears to act as a vector transferring PBTs from the water to the food web, increasing risk throughout the marine food web, including humans. Because of the extremely long lifetime of plastic and PBTs in the ocean, prevention strategies are vital to minimizing these risks.

ORDEM 3.0 and the Risk of High-Density Debris

Science.gov (United States)

Matney, Mark; Anz-Meador, Philip

2014-01-01

NASA’s Orbital Debris Engineering Model was designed to calculate orbital debris fluxes on spacecraft in order to assess collision risk. The newest of these models, ORDEM 3.0, has a number of features not present in previous models. One of the most important is that the populations and fluxes are now broken out into material density groups. Previous models concentrated on debris size alone, but a particle’s mass and density also determine the amount of damage it can cause. ORDEM 3.0 includes a high-density component, primarily consisting of iron/steel particles that drive much of the risk to spacecraft. This paper will outline the methods that were used to separate and identify the different densities of debris, and how these new densities affect the overall debris flux and risk.

Sensitivity Analysis of Launch Vehicle Debris Risk Model

Science.gov (United States)

Gee, Ken; Lawrence, Scott L.

2010-01-01

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

Development of tsunami fragility evaluation methods by large scale experiments. Part 2. Validation of the applicability of evaluation methods of impact force due to tsunami floating debris

International Nuclear Information System (INIS)

Takabatake, Daisuke; Kihara, Naoto; Kaida, Hideki; Miyagawa, Yoshinori; Ikeno, Masaaki; Shibayama, Atsushi

2015-01-01

In order to examine the applicability of the existing estimation equations of the impact force due to tsunami floating debris, the collision tests are carried out. In the experiments, logs and full-scale light car are used. In this report, two types of existing equations, one is based on the Young's module of the debris (Eq.A) and the other one is based on the stiffness of the debris (Eq.B), are focused on. The estimated impact forces using Eq.A with log's Young module obtained by the material test agree with measured forces obtained by the collision test. But Eq.A does not applicate to a car because it is not easy to determine the Young's module of a car. On the other hand, the estimated impact forces using Eq.B with car's stiffness obtained by the static loading test agree with measured forces obtained by the collision test. This indicates that Eq.B unable us to estimate impact force of the floating debris such as car if the stiffness of the debris is determined. (author)

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

Science.gov (United States)

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

Quantitative assessment of apical debris extrusion and intracanal debris in the apical third, using hand instrumentation and three rotary instrumentation systems.

Science.gov (United States)

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.

Woody debris along an upland chromosequence in boreal Manitoba and its impact on long-term carbon storage

Energy Technology Data Exchange (ETDEWEB)

Manies, K. L.; Harden, J. W. [US Geological Survey, Menlo Park, CA (United States); Bond-Lamberty, B. P. [University of Wisconsin, Dept. of Forest Ecology and Management, Madison, WI (United States); O' Neill, K. P. [USDA Agricultural Research Service, Appalachian Farming Systems Research Center, Beaver, WV (United States)

2005-02-01

The amount of standing dead and downed woody debris along an upland chromosequence was measured in an effort to investigate the role of fire-killed woody debris as a source of soil carbon in black spruce stands in Manitoba. Based on the measurement data and existing primary production values, a mass balance model was used to assess the potential impact of fire-killed wood on long-term carbon storage at this site. Long-term carbon was represented by the amount of carbon stored in deeper soil organic layers, persisting over millenia. Between 10 and 60 per cent of the deep-soil carbon was estimated to have been derived from wood biomass. The actual amount appears to be most affected by fire return interval, decay rate of wood, the amount of net primary production, and the decay rate of the post-fire carbon pool. Although the model was less sensitive to fire consumption rates and to rates at which standing dead wood becomes woody debris, all model runs clearly established that woody debris plays an important role in long-term carbon storage in this area. 53 refs., 4 tabs., 4 figs.

POST Earthquake Debris Management — AN Overview

Science.gov (United States)

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

Impact risk assessment for the ATV using ESABASE/DEBRIS

Science.gov (United States)

Beltrami Karlezi, P.; Drolshagen, G.; Lambert, M.

2001-10-01

The European Space Agency ESA participates in the International Space Station with various programs, one of them being the Automated Transfer Vehicle (ATV). The ATV is an unmanned servicing and logistics vehicle launched on Ariane 5 and designed to fulfil different roles like cargo transport, re-supply of fuel and consumables and orbit re-boost of the International Space Station (ISS). For this reason it is important that the risks imposed on these modules by meteoroids and orbital debris are calculated accurately. Following such calculations the Meteoroid and Orbital Debris Protection System (M/ODPS) can be optimised. This paper presents the results of the risk assessment of meteoroids and space debris for the ATV spacecraft attached to the ISS using different shield configurations. The results are presented as the probability of no penetration (PNP) for each component and each configuration. They are compared to a target PNP requirement of 0.999 for 135 days and the weight penalty produced by the extra shielding is given.

Common factors drive disease and coarse woody debris dynamics in forests impacted by sudden oak death

Science.gov (United States)

Richard C. Cobb; Maggie N. Chan; Ross K. Meentemeyer; David M. Rizzo

2011-01-01

Disease ecology has made important steps in describing how epidemiological processes control the impact of pathogens on populations and communities but fewer field or theoretical studies address disease effects at the ecosystem level. We demonstrate that the same epidemiological mechanisms drive disease intensity and coarse woody debris (CWD) dynamics...

Debris flow risk mitigation by the means of rigid and flexible barriers – experimental tests and impact analysis

Directory of Open Access Journals (Sweden)

L. Canelli

2012-05-01

Full Text Available The impact of a debris flow on a structure can have disastrous effects because of the enormous destructive potential of this type of phenomenon. Although the introduction of risk mitigation structures such as the Sabo Dam, the filter dam and more recently flexible barriers is usual, there are very few methods that are universally recognized for the safe design of such structures. This study presents the results of experimental tests, conducted with the use of a specifically created flume, in order to obtain detailed knowledge of the mechanical aspects, and to analyze the dynamics of the impact of a debris flow on different types of structures. The analyses of the tests, together with the calculation of the thrust caused by the flow, have made it possible to analyze the dynamics of the impact, which has shown differing effects, on the basis of the type of barrier that has been installed.

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

Science.gov (United States)

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

Monitoring the abundance of plastic debris in the marine environment

OpenAIRE

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

2009-01-01

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

Local Impact Simulation of SC Wall Structures using Aircraft Engine Projectile

International Nuclear Information System (INIS)

Chung, Chulhun; Lee, Jungwhee; Lee, Hanjoo; Jung, Raeyoung; Hyun, Changhun

2013-01-01

SC wall structure developed for nuclear power plant buildings consists of plain concrete and two steel plates on both surface of the concrete, while RC structure consists of re bar and concrete. SC structure has higher scabbing resistance than RC structure due to the action of steel plate on the rear side of impact. Therefore SC structure is known as more effective structure from the viewpoint of aircraft crash than RC structure. However, most of the recent researches and experiments about local impact damage deal with RC structures, and the effect of re bar and steel plate is not considered reasonably. Although Walter et al. and Make-work et al. suggested a formula for evaluating perforation depth of steel plate covered RC walls, most of the previous researches about SC structure are focused on perforation and scabbing due to the impact of hard projectile, rather than soft projectile such as an aircraft. In this research a soft projectile, i. e. aircraft engine, is utilized for impact simulation of RC and SC walls. To evaluate local damage of SC wall structures, parametric study with the variables of wall thickness and steel ratio of the cover plate is performed, and the results are compared with those of RC structures. Since scabbing was prevented by the steel plates, penetration mode of damage was observed in SC walls while scabbing damage was occurred in RC walls. It is confirmed that the rear steel plate not only contains concrete debris, but also reduces the internal damage of the concrete walls. Penetration depth of SC walls did not largely vary due to the increasing steel ratio, and similar results to RC walls were observed when the wall thickness is larger than a certain value since the impact resistance of SC wall is mainly governed by the thickness of concrete part. Therefore, it is expected that similar level of impact resistance to RC structure can be produced with the minimum thickness of steel plates of SC structure. According to these results, SC

Feature test report for the Small Debris Collection and Packaging System

International Nuclear Information System (INIS)

Brisbin, S.A.

1995-01-01

The Spent Nuclear Fuel Equipment Engineering group performed feature testing of the Small Debris Collection and Packaging System (SDCPS) in the 305 Cold Test Facility from January 30, 1995, to February 1, 1995. Feature testing of the Small Debris Collection and Packaging System (SDCPS) was performed for the following reasons: To assess the feasibility of using ''drop-out'' vessels to collect small debris (<2.5 cm) in MK-II fuel canisters while transferring sludge to the Weasel Pit. To evaluate system performance under conditions similar to those in the K-Basins (e.g. submerged under 4.9 meters of water and operated with long handled tools) while using a surrogate sludge mixed with debris. To determine if canister weight could be used to predict the volume of sludge and/or debris contained within the canisters during system operation

Protecting AREVA ATRIUM™ BWR fuel from debris fretting failure

International Nuclear Information System (INIS)

Cole, Steven E.; Garner, Norman L.; Lippert, Hans-Joachim; Graebert, Rüdiger; Mollard, Pierre; Hahn, Gregory C.

2014-01-01

Historically, debris fretting has been the leading cause of fuel rod failure in BWR fuel assemblies, costing the industry millions of dollars in lost generation and negatively impacting the working area of plant site personnel. In this paper the focus will be on recent BWR fuel product innovation designed to eliminate debris related failures. Experience feedback from more than three decades of operation history with non-line-of-sight FUELGUARD™ lower tie plate debris filters will be presented. The development and relative effectiveness of successive generations of filtration technology will be discussed. It will be shown that modern, state of the art debris filters are an effective defense against debris fretting failure. Protective measures extend beyond inlet nozzle debris filters. The comprehensive debris resistance features built into AREVA’s newest fuel design, the ATRIUM™ 11, reduce the overall risk of debris entrapment as well as providing a degree of protection from debris that may fall down on the fuel assembly from above, e.g., during refueling operations. The positive recent experience in a debris sensitive plant will be discussed showing that the combination of advanced fuel technology and a robust foreign material exclusion program at the reactor site can eliminate the debris fretting failure mechanism. (author)

Space Debris Removal: A Game Theoretic Analysis

Directory of Open Access Journals (Sweden)

Richard Klima

2016-08-01

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

Monitoring the abundance of plastic debris in the marine environment.

Science.gov (United States)

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

2009-07-27

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

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

Science.gov (United States)

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

Sampling supraglacial debris thickness using terrestrial photogrammetry

Science.gov (United States)

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.

Characteristics Study of In-Situ Capacitive Sensor for Monitoring Lubrication Oil Debris.

Science.gov (United States)

Han, Zhibin; Wang, Yishou; Qing, Xinlin

2017-12-08

As an essential part of engine health monitoring (EHM), online lubrication oil debris monitoring has recently received great attention for the assessment of rotating and reciprocating parts in aero-engines, due to its high integration, low cost and safe characteristics. However, it is be a challenge to find a suitable sensor operating in such a complex environment. We present an unconventional novel approach, in which a cylinder capacitive sensor is designed and integrated with the pipeline of an engine lubrication system, so that the capacitive sensor can effectively detect changes in the lubrication oil condition. In this paper, an attempt to illustrate the performance characteristics of the developed cylinder capacitive sensor is made, through an experiment system that simulates a real scenario of a lubrication oil system. The main aim of the research was to qualitatively describe the relationship between the sensor parameter and the lubrication oil debris. In addition, the effect of the temperature and flow rate of the lubrication oil on capacitance change was performed by several experiments and we figured out a compensation method. The experimental results demonstrated that the cylinder capacitive sensor can potentially be used for lubrication oil debris monitoring of the health condition of an aero-engine.

Fiber-Optic Micrometeoroid/Orbital Debris Impact Detector System

Science.gov (United States)

Christiansen, Eric L.; Tennyson, R. C.; Morison, W. D.

2012-01-01

A document describes a reliable, lightweight micrometeoroid/orbital debris (MMOD) detection system that can be located at strategic positions of "high consequence" to provide real-time warning of a penetration, its location, and the extent of the damage to a spacecraft. The concept is to employ fiber-optic sensors to detect impact damage and penetration of spacecraft structures. The fibers are non-electrical, employ light waves, and are immune to electromagnetic interference. The fiber-optic sensor array can be made as a stand-alone product, being bonded to a flexible membrane material or a structure that is employed as a MMOD shield material. The optical sensors can also be woven into hybrid MMOD shielding fabrics. The glass fibers of the fiber-optic sensor provide a dual purpose in contributing to the breakup of MMOD projectiles. The grid arrays can be made in a modular configuration to provide coverage over any area desired. Each module can be connected to a central scanner instrument and be interrogated in a continuous or periodic mode.

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

International Nuclear Information System (INIS)

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

2010-01-01

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

As main meal for sperm whales: plastics debris.

Science.gov (United States)

de Stephanis, Renaud; Giménez, Joan; Carpinelli, Eva; Gutierrez-Exposito, Carlos; Cañadas, Ana

2013-04-15

Marine debris has been found in marine animals since the early 20th century, but little is known about the impacts of the ingestion of debris in large marine mammals. In this study we describe a case of mortality of a sperm whale related to the ingestion of large amounts of marine debris in the Mediterranean Sea (4th published case worldwide to our knowledge), and discuss it within the context of the spatial distribution of the species and the presence of anthropogenic activities in the area that could be the source of the plastic debris found inside the sperm whale. The spatial distribution modelled for the species in the region shows that these animals can be seen in two distinct areas: near the waters of Almería, Granada and Murcia and in waters near the Strait of Gibraltar. The results shows how these animals feed in waters near an area completely flooded by the greenhouse industry, making them vulnerable to its waste products if adequate treatment of this industry's debris is not in place. Most types of these plastic materials have been found in the individual examined and cause of death was presumed to be gastric rupture following impaction with debris, which added to a previous problem of starvation. The problem of plastics arising from greenhouse agriculture should have a relevant section in the conservation plans and should be a recommendation from ACCOBAMS due to these plastics' and sperm whales' high mobility in the Mediterranean Sea. Copyright © 2013 Elsevier Ltd. All rights reserved.

Analysis of Debris Trajectories at the Scaled Wind Farm Technology (SWiFT) Facility

Energy Technology Data Exchange (ETDEWEB)

White, Jonathan R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Burnett, Damon J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-01-01

Sandia National Laboratories operates the Scaled Wind Farm Technology Facility (SWiFT) on behalf of the Department of Energy Wind and Water Power Technologies Office. An analysis was performed to evaluate the hazards associated with debris thrown from one of SWiFT’s operating wind turbines, assuming a catastrophic failure. A Monte Carlo analysis was conducted to assess the complex variable space associated with debris throw hazards that included wind speed, wind direction, azimuth and pitch angles of the blade, and percentage of the blade that was separated. In addition, a set of high fidelity explicit dynamic finite element simulations were performed to determine the threshold impact energy envelope for the turbine control building located on-site. Assuming that all of the layered, independent, passive and active engineered safety systems and administrative procedures failed (a 100% failure rate of the safety systems), the likelihood of the control building being struck was calculated to be less than 5/10,000 and ballistic simulations showed that the control building would not provide passive protection for the majority of impact scenarios. Although options exist to improve the ballistic resistance of the control building, the recommendation is not to pursue them because there is a low probability of strike and there is an equal likelihood personnel could be located at similar distances in other areas of the SWiFT facility which are not passively protected, while the turbines are operating. A fenced exclusion area has been created around the turbines which restricts access to the boundary of the 1/100 strike probability. The overall recommendation is to neither relocate nor improve passive protection of the control building as the turbine safety systems have been improved to have no less than two independent, redundant, high quality engineered safety systems. Considering this, in combination with a control building strike probability of less than 5/10,000, the

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

Science.gov (United States)

Karacalioglu, Arif Goektug; Stupl, Jan

2016-01-01

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

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

Science.gov (United States)

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

Advanced structural wind engineering

CERN Document Server

Kareem, Ahsan

2013-01-01

This book serves as a textbook for advanced courses as it introduces state-of-the-art information and the latest research results on diverse problems in the structural wind engineering field. The topics include wind climates, design wind speed estimation, bluff body aerodynamics and applications, wind-induced building responses, wind, gust factor approach, wind loads on components and cladding, debris impacts, wind loading codes and standards, computational tools and computational fluid dynamics techniques, habitability to building vibrations, damping in buildings, and suppression of wind-induced vibrations. Graduate students and expert engineers will find the book especially interesting and relevant to their research and work.

The Orbital Debris Problem and the Challenges for Environment Remediation

Science.gov (United States)

Liou, J.-C.

2014-01-01

LEO debris population will continue to increase even with a good implementation of the commonly-adopted mitigation measures. The root-cause of the increase is catastrophic collisions involving large/massive intact objects (rocket bodies or spacecraft). The major mission-ending risks for most operational spacecraft, however, come from impacts with debris just above the threshold of the protection shields (5-mm to 1-cm). A solution-driven approach is to seek: Concepts for removal of massive intacts with high P(collision); Concepts capable of preventing collisions involving intacts; Concepts for removal of 5-mm to 1-cm debris; Enhanced impact protection shields for valuable space assets. Key questions for remediation consideration of orbital debris: What is the acceptable threat level? What are the mission objectives? What is the appropriate roadmap/timeframe for remediation? Support advanced technology development when an economically viable approach is identified. Address non-technical issues, such as policy, coordination, ownership, legal, and liability at the national and international levels.

Conditioning of metallic Magnox fuel element debris

International Nuclear Information System (INIS)

Kaye, C.J.

1983-01-01

The conditioning of metallic Magnox debris poses particular problems arising from its chemical reactivity and from the presence in discrete amounts of highly radioactive components. The treatment of this waste is currently being studied by the Central Electricity Generating Board. Following retrieval from store it is envisaged that the debris will be dried and comminuted to facilitate the removal for further storage of the highly active components from the bulk debris. A satisfactory means of sorting the debris appears to be by magnetic induction. The relatively low activity but potentially reactive Magnox will then be directly encapsulated prior to disposal off-site. Currently the only disposal route open for this waste is to the deep ocean. Matrices for encapsulating Magnox have been developed and others are under investigation. The desirable features of such matrices include low chemical reactivity and impermeability to water. The methods used to characterize the resultant waste forms and the results obtained are presented. Thermosetting polymers produce suitable waste forms for sea disposal, exhibiting high mechanical strength and resistance to leaching, and possessing very low chemical reactivity with respect to the Magnox waste. Low viscosity matrices are advantageous from the point of view of the process plant engineering as they enable the comminuted waste to be directly encapsulated. (author)

USA Space Debris Environment, Operations, and Research Updates

Science.gov (United States)

Liou, J.-C.

2018-01-01

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

NASA Orbital Debris Large-Object Baseline Population in ORDEM 3.0

Science.gov (United States)

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

2013-01-01

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

Space Debris & its Mitigation

Science.gov (United States)

Kaushal, Sourabh; Arora, Nishant

2012-07-01

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

Transporting fuel debris from TMI-2 to INEL

International Nuclear Information System (INIS)

Quinn, G.J.; Burton, H.M.; Bixby, W.W.; McIntosh, T.W.; McGoff, O.J.; Barkonic, R.J.; Henrie, J.O.

1986-06-01

Transportation of the damaged fuel from Unit 2 of Three Mile Island (TMI-2) presented noteworthy technical challenges involving complex institutional issues. The program resulted from both a need to package and remove the accident debris and also the opportunity to receive and study damaged core components. These combined to establish the safe transport of the TMI-2 fuel debris as a high priority for many diverse organizations. The capability of the sending and receiving facilities to handle spent fuel transport casks in the most cost-effective manner was assessed and resulted in the development by Nuclear Packaging Inc. (NuPac) of the NuPac 125-B rail cask. This paper reviews the technical challenges in preparation of the TMI-2 core debris for transport from TMI-2 to the Idaho National Engineering Laboratory (INEL) and receipt and storage of that material at INEL. Challenges discussed include design and testing of fuel debris canisters; design, fabrication and licensing of a new rail cask for spent fuel transport; cask loading operations, equipment and facilities at TMI-2; transportation logistics; and, receipt, storage and core examination operations at INEL. 10 refs

Estimating Foreign-Object-Debris Density from Photogrammetry Data

Science.gov (United States)

Long, Jason; Metzger, Philip; Lane, John

2013-01-01

Within the first few seconds after launch of STS-124, debris traveling vertically near the vehicle was captured on two 16-mm film cameras surrounding the launch pad. One particular piece of debris caught the attention of engineers investigating the release of the flame trench fire bricks. The question to be answered was if the debris was a fire brick, and if it represented the first bricks that were ejected from the flame trench wall, or was the object one of the pieces of debris normally ejected from the vehicle during launch. If it was typical launch debris, such as SRB throat plug foam, why was it traveling vertically and parallel to the vehicle during launch, instead of following its normal trajectory, flying horizontally toward the north perimeter fence? By utilizing the Runge-Kutta integration method for velocity and the Verlet integration method for position, a method that suppresses trajectory computational instabilities due to noisy position data was obtained. This combination of integration methods provides a means to extract the best estimate of drag force and drag coefficient under the non-ideal conditions of limited position data. This integration strategy leads immediately to the best possible estimate of object density, within the constraints of unknown particle shape. These types of calculations do not exist in readily available off-the-shelf simulation software, especially where photogrammetry data is needed as an input.

Reassessment of debris ingestion effects on emergency core cooling-system pump performance

International Nuclear Information System (INIS)

Sciacca, F.W.; Rao, D.V.

2004-01-01

A study sponsored by the United States (US) Nuclear Regulatory Commission (NRC) was performed to reassess the effects of ingesting loss of coolant accident (LOCA) generated materials into emergency core cooling system (ECCS) pumps and the subsequent impact of this debris on the pumps' ability to provide long-term cooling to the reactor core. ECCS intake systems have been designed to screen out large post-LOCA debris materials. However, small-sized debris can penetrate these intake strainers or screens and reach critical pump components. Prior NRC-sponsored evaluations of possible debris and gas ingestion into ECCS pumps and attendant impacts on pump performance were performed in the early 1980's. The earlier study focused primarily on pressurised water reactor (PWR) ECCS pumps. This issue was revisited both to factor in our improved knowledge of LOCA generated debris and to address specifically both boiling water reactor (BWR) and PWR ECCS pumps. This study discusses the potential effects of ingested debris on pump seals, bearing assemblies, cyclone debris separators, and seal cooling water subsystems. This assessment included both near-term (less than one hour) and long-term (greater than one hour) effects introduced by the postulated LOCA. The work reported herein was performed during 1996-1997. (authors)

Influence of check dams on debris-flow run-out intensity

Directory of Open Access Journals (Sweden)

A. Remaître

2008-12-01

Full Text Available Debris flows are very dangerous phenomena claiming thousands of lives and millions of Euros each year over the world. Disaster mitigation includes non-structural (hazard mapping, insurance policies, active structural (drainage systems and passive structural (check dams, stilling basins countermeasures. Since over twenty years, many efforts are devoted by the scientific and engineering communities to the design of proper devices able to capture the debris-flow volume and/or break down the energy. If considerable theoretical and numerical work has been performed on the size, the shape and structure of check dams, allowing the definition of general design criteria, it is worth noting that less research has focused on the optimal location of these dams along the debris-flow pathway.

In this paper, a methodological framework is proposed to evaluate the influence of the number and the location of the check dams on the reduction of the debris-flow intensity (in term of flow thickness, flow velocity and volume. A debris-flow model is used to simulate the run-out of the debris flow. The model uses the Janbu force diagram to resolve the force equilibrium equations; a bingham fluid rheology is introduced and represents the resistance term. The model has been calibrated on two muddy debris-flow events that occurred in 1996 and 2003 at the Faucon watershed (South French Alps.

Influence of the check dams on the debris-flow intensity is quantified taking into account several check dams configurations (number and location as input geometrical parameters. Results indicate that debris-flow intensity is decreasing with the distance between the source area and the first check dams. The study demonstrates that a small number of check dams located near the source area may decrease substantially the debris-flow intensity on the alluvial fans.

Impact of high-risk conjunctions on Active Debris Removal target selection

OpenAIRE

Lidtke, Aleksander A.; Lewis, Hugh G.; Armellin, Roberto

2015-01-01

All rights reserved.Space debris simulations show that if current space launches continue unchanged, spacecraft operations might become difficult in the congested space environment. It has been suggested that Active Debris Removal (ADR) might be necessary in order to prevent such a situation. Selection of objects to be targeted by ADR is considered important because removal of non-relevant objects will unnecessarily increase the cost of ADR. One of the factors to be used in this ADR target se...

Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy

Directory of Open Access Journals (Sweden)

P. Budetta

2010-09-01

Full Text Available On 10 January 2003, a rockfall of approximately 10 m³ affected a cliff some 25 m high located along the northern slopes of Mt. St. Angelo (Nocera Inferiore, province of Salerno in the southern Italian region of Campania. The impact of boulders on the lower sector of the slope, along which detrital-pyroclastic soils outcrop, triggered a small channelled debris flow of about 500 m³. Fortunately, no damage nor victims resulted from the landslide. Several marks of the impacts were observed at the cliff toe and outside the collapsed area, and the volumes of some fallen boulders were subsequently measured. By means of in-situ surveys, it was possible to reconstruct the cliff's geo-structural layout in detail. A rockfall back-analysis was subsequently performed along seven critical profiles of the entire slope (surface area of about 4000 m². The results of this numerical modelling using the lumped-mass method were then used to map the kinetic iso-energy curves. In the triggering area of the debris flow, for a falling boulder of 1 m³, the mean kinetic energy was estimated at 120 kJ, this value being equivalent to an impact force, on an inclined surface, of some 800 kN. After landing, due to the locally high slope gradient (about 45°, and low angle of trajectory at impact (about 23°, some boulders slid down the slope as far as the endpoints. The maximum depth of penetration into the ground by a sliding block was estimated at about 16 cm. Very likely, owing to the high impact force of boulders on the saturated soil slope outcropping at the cliff base, the debris flow was triggered under undrained loading conditions. Initial failure was characterized by a translational slide involving a limited, almost elliptical area where the pyroclastic cover shows greater thickness in comparison with the surrounding areas.

Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy

Science.gov (United States)

Budetta, P.

2010-09-01

On 10 January 2003, a rockfall of approximately 10 m3 affected a cliff some 25 m high located along the northern slopes of Mt. St. Angelo (Nocera Inferiore, province of Salerno) in the southern Italian region of Campania. The impact of boulders on the lower sector of the slope, along which detrital-pyroclastic soils outcrop, triggered a small channelled debris flow of about 500 m3. Fortunately, no damage nor victims resulted from the landslide. Several marks of the impacts were observed at the cliff toe and outside the collapsed area, and the volumes of some fallen boulders were subsequently measured. By means of in-situ surveys, it was possible to reconstruct the cliff's geo-structural layout in detail. A rockfall back-analysis was subsequently performed along seven critical profiles of the entire slope (surface area of about 4000 m2). The results of this numerical modelling using the lumped-mass method were then used to map the kinetic iso-energy curves. In the triggering area of the debris flow, for a falling boulder of 1 m3, the mean kinetic energy was estimated at 120 kJ, this value being equivalent to an impact force, on an inclined surface, of some 800 kN. After landing, due to the locally high slope gradient (about 45°), and low angle of trajectory at impact (about 23°), some boulders slid down the slope as far as the endpoints. The maximum depth of penetration into the ground by a sliding block was estimated at about 16 cm. Very likely, owing to the high impact force of boulders on the saturated soil slope outcropping at the cliff base, the debris flow was triggered under undrained loading conditions. Initial failure was characterized by a translational slide involving a limited, almost elliptical area where the pyroclastic cover shows greater thickness in comparison with the surrounding areas.

Debris flows associated with the 2015 Gorkha Earthquake in Nepal

Science.gov (United States)

Dahlquist, M. P.; West, A. J.; Martinez, J.

2017-12-01

Debris flows are a primary driver of erosion and a major geologic hazard in many steep landscapes, particularly near the headwaters of rivers, and are generated in large numbers by extreme events. The 2015 Mw 7.8 Gorkha Earthquake triggered 25,000 coseismic landslides in central Nepal. During the ensuing monsoon, sediment delivered to channels by landslides was mobilized in the heavy rains, and new postseismic landslides were triggered in rock weakened by the shaking. These coseismic and postseismic landslide-generated debris flows form a useful dataset for studying the impact and behavior of debris flows on one of the most active landscapes on Earth. Debris flow-dominated channel reaches are generally understood to have a topographic signature recognizable in slope-area plots and distinct from fluvial channels, but in examining debris flows associated with the Gorkha earthquake we find they frequently extend into reaches with geometry typically associated with fluvial systems. We examine a dataset of these debris flows, considering whether they are generated by coseismic or postseismic landslides, whether they are likely to be driving active incision into bedrock, and whether their channels correspond with those typically associated with debris flows. Preliminary analysis of debris flow channels in Nepal suggests there may be systematic differences in the geometry of channels containing debris flows triggered by coseismic versus postseismic landslides, which potentially holds implications for hazard analyses and the mechanics behind the different debris flow types.

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

Science.gov (United States)

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.

PVD TBC experience on GE aircraft engines

Science.gov (United States)

Maricocchi, Antonio; Bartz, Andi; Wortman, David

1995-01-01

The higher performance levels of modern gas turbine engines present significant challenges in the reliability of materials in the turbine. The increased engine temperatures required to achieve the higher performance levels reduce the strength of the materials used in the turbine sections of the engine. Various forms of thermal barrier coatings (TBC's) have been used for many years to increase the reliability of gas turbine engine components. Recent experience with the physical vapor deposition (PVD) process using ceramic material has demonstrated success in extending the service life of turbine blades and nozzles. Engine test results of turbine components with a 125 micron (0.005 in) PVD TBC have demonstrated component operating temperatures of 56-83 C (100-150 F) lower than non-PVD TBC components. Engine testing has also revealed the TBC is susceptible to high angle particle impact damage. Sand particles and other engine debris impact the TBC surface at the leading edge of airfoils and fracture the PVD columns. As the impacting continues, the TBC erodes away in local areas. Analysis of the eroded areas has shown a slight increase in temperature over a fully coated area, however a significant temperature reduction was realized over an airfoil without TBC.

A 1 cm space debris impact onto the Sentinel-1A solar array

Science.gov (United States)

Krag, H.; Serrano, M.; Braun, V.; Kuchynka, P.; Catania, M.; Siminski, J.; Schimmerohn, M.; Marc, X.; Kuijper, D.; Shurmer, I.; O'Connell, A.; Otten, M.; Muñoz, Isidro; Morales, J.; Wermuth, M.; McKissock, D.

2017-08-01

Sentinel-1A is a 2-ton spacecraft of the Copernicus Earth observation program operated by ESA's Space Operations Centre in Darmstadt, Germany. Sentinel-1A and its sister spacecraft Sentinel-1B operate in a sun-synchronous orbit at about 700 km altitude. On 2016/08/23 17:07:37 UTC, Sentinel-1A suffered from an anomaly resulting in a sudden permanent partial power loss and significant impulsive orbit and attitude changes. A deeper investigation identified that an impulsive orbit change against flight direction of 0.7 mm/s, estimated at the time of the event, gave the best results in terms of GPS residuals. At the same time, a peak attitude off-pointing of 0.7° (around the spacecraft yaw axis) and peak attitude rate increase of 0.04°/s (around the same axis) were observed. The simultaneous occurrence of these anomalies, starting from a sudden attitude change and ending with a permanent partial power loss, made an MMOD (Micro-Meteoroid and Orbital Debris) impact onto a solar array a possible explanation for this event. While the spacecraft is able to continue its mission nominally, a detailed investigation involving ESA's Space Debris and Flight Dynamics experts was conducted. An MMOD impact as an explanation gained further credibility, due to the pictures of the solar array taken by the on-board camera displaying a significant damage area. On September 7th, JSpOC (US Joint Space Operations Centre) informed SDO on 8 tracked fragments that are considered to be released by Sentinel-1A after the impact. This paper addresses the analysis that was performed on the data characterising the attitude and orbit change, the on-board camera image, and the tracked fragments. The data helped to identify the linear momentum vector while a flux analysis helped to identify the origin of the impactor and allowed to understand its mass and size characteristics.

Corporate social responsibility in marine plastic debris governance.

Science.gov (United States)

Landon-Lane, Micah

2018-02-01

This paper explores the governance characteristics of marine plastic debris, some of the factors underpinning its severity, and examines the possibility of harnessing corporate social responsibility (CSR) to manage plastic use within the contextual attitudes of a contemporary global society. It argues that international and domestic law alone are insufficient to resolve the "wicked problem" of marine plastic debris, and investigates the potential of the private sector, through the philosophy of CSR, to assist in reducing the amount and impacts of marine plastic debris. To illustrate how CSR could minimise marine plastic pollution, an industry-targeted code of conduct was developed. Applying CSR would be most effective if implemented in conjunction with facilitating governance frameworks, such as supportive governmental regulation and non-governmental partnerships. This study maintains that management policies must be inclusive of all stakeholders if they are to match the scale and severity of the marine plastic debris issue. Copyright © 2017 Elsevier Ltd. All rights reserved.

An Approach to Predict Debris Flow Average Velocity

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Chen Cao

2017-03-01

Full Text Available Debris flow is one of the major threats for the sustainability of environmental and social development. The velocity directly determines the impact on the vulnerability. This study focuses on an approach using radial basis function (RBF neural network and gravitational search algorithm (GSA for predicting debris flow velocity. A total of 50 debris flow events were investigated in the Jiangjia gully. These data were used for building the GSA-based RBF approach (GSA-RBF. Eighty percent (40 groups of the measured data were selected randomly as the training database. The other 20% (10 groups of data were used as testing data. Finally, the approach was applied to predict six debris flow gullies velocities in the Wudongde Dam site area, where environmental conditions were similar to the Jiangjia gully. The modified Dongchuan empirical equation and the pulled particle analysis of debris flow (PPA approach were used for comparison and validation. The results showed that: (i the GSA-RBF predicted debris flow velocity values are very close to the measured values, which performs better than those using RBF neural network alone; (ii the GSA-RBF results and the MDEE results are similar in the Jiangjia gully debris flow velocities prediction, and GSA-RBF performs better; (iii in the study area, the GSA-RBF results are validated reliable; and (iv we could consider more variables in predicting the debris flow velocity by using GSA-RBF on the basis of measured data in other areas, which is more applicable. Because the GSA-RBF approach was more accurate, both the numerical simulation and the empirical equation can be taken into consideration for constructing debris flow mitigation works. They could be complementary and verified for each other.

Plastic debris ingestion by marine catfish: an unexpected fisheries impact.

Science.gov (United States)

Possatto, Fernanda E; Barletta, Mário; Costa, Monica F; do Sul, Juliana A Ivar; Dantas, David V

2011-05-01

Plastic marine debris is a pervasive type of pollution. River basins and estuaries are a source of plastics pollution for coastal waters and oceans. Estuarine fauna is therefore exposed to chronic plastic pollution. Three important catfish species [Cathorops spixii (N=60), Cathorops agassizii (N=60) and Sciades herzbergii (N=62)] from South Western Atlantic estuaries were investigated in a tropical estuary of the Brazilian Northeast in relation to their accidental ingestion of plastic marine debris. Individuals from all three species had ingested plastics. In C. spixii and C. agassizii, 18% and 33% of individuals had plastic debris in their stomachs, respectively. S. herzbergii showed 18% of individuals were contaminated. All ontogenetic phases (juveniles, sub-adults and adults) were contaminated. Nylon fragments from cables used in fishery activities (subsistence, artisanal and commercial) played a major role in this contamination. These catfish spend their entire life cycles within the estuary and are an important feeding resource for larger, economically important, species. It is not yet possible to quantify the scale and depth of the consequences of this type of pollution. However, plastics are well known threat to living resources in this and other estuaries. Conservation actions will need to from now onto take plastics pollution into consideration. Copyright © 2011 Elsevier Ltd. All rights reserved.

Engineering of complex systems: The impact of systems engineering at NASA

Science.gov (United States)

Kludze, Ave-Klutse Kodzo Paaku

The "true" impact or value of systems engineering to an organization unfortunately appears not to have been well-studied and understood. The principles of systems engineering are highly encouraged by NASA at all levels, and most practitioners, both internal and external to NASA, intuitively "believe" it adds some value to the development of complex systems by producing them faster, better and cheaper. This research, in trying to fill a gap that exists in the systems engineering literature, analyzes data collected within NASA and other sources external to NASA (INCOSE) for comparisons. Analyses involving a number of case studies performed on selected NASA projects are presented to draw attention to the impact systems engineering had or could have had on these projects. This research clearly shows that systems engineering does add value to projects within and outside NASA. The research results further demonstrate that systems engineering has been beneficial not only to NASA but also to organizations within which INCOSE members work. It was determined, however, that systems engineering does not operate in a vacuum and may not always guarantee success through mere application. During this research, it was discovered that the lack of or inadequate application of systems engineering in the development of complex systems may result in cost overruns, poor technical performance, project delays, and in some cases unmitigated risk with disastrous consequences including the loss of life and property. How much is saved (in terms of cost, schedule) or improved (in terms of technical performance) as a result of its implementation may never be known precisely, but by indirectly measuring its value or impact on a project, percentages of project budget spent on systems engineering activities and any schedule reductions or performance enhancements realized could be determined. According to this research, systems engineering is not a waste of time and resources; in most cases, it is

Roads at risk - the impact of debris flows on road network reliability and vulnerability in southern Norway

Science.gov (United States)

Meyer, Nele Kristin; Schwanghart, Wolfgang; Korup, Oliver

2014-05-01

Norwegian's road network is frequently affected by debris flows. Both damage repair and traffic interruption generate high economic losses and necessitate a rigorous assessment of where losses are expected to be high and where preventive measures should be focused on. In recent studies, we have developed susceptibility and trigger probability maps that serve as input into a hazard calculation at the scale of first-order watersheds. Here we combine these results with graph theory to assess the impact of debris flows on the road network of southern Norway. Susceptibility and trigger probability are aggregated for individual road sections to form a reliability index that relates to the failure probability of a link that connects two network vertices, e.g., road junctions. We define link vulnerability as a function of traffic volume and additional link failure distance. Additional link failure distance is the extra length of the alternative path connecting the two associated link vertices in case the network link fails and is calculated by a shortest-path algorithm. The product of network reliability and vulnerability indices represent the risk index. High risk indices identify critical links for the Norwegian road network and are investigated in more detail. Scenarios demonstrating the impact of single or multiple debris flow events are run for the most important routes between seven large cities in southern Norway. First results show that the reliability of the road network is lowest in the central and north-western part of the study area. Road network vulnerability is highest in the mountainous regions in central southern Norway where the road density is low and in the vicinity of cities where the traffic volume is large. The scenarios indicate that city connections that have their shortest path via routes crossing the central part of the study area have the highest risk of route failure.

Predicting the occurrence of channelized debris flow by an integrated cascading model: A case study of a small debris flow-prone catchment in Zhejiang Province, China

Science.gov (United States)

Wei, Zhen-lei; Xu, Yue-Ping; Sun, Hong-yue; Xie, Wei; Wu, Gang

2018-05-01

Excessive water in a channel is an important factor that triggers channelized debris flows. Floods and debris flows often occur in a cascading manner, and thus, calculating the amount of runoff accurately is important for predicting the occurrence of debris flows. In order to explore the runoff-rainfall relationship, we placed two measuring facilities at the outlet of a small, debris flow-prone headwater catchment to explore the hydrological response of the catchment. The runoff responses generally consisted of a rapid increase in runoff followed by a slower decrease. The peak runoff often occurred after the rainfall ended. The runoff discharge data were simulated by two different modeling approaches, i.e., the NAM model and the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model. The results showed that the NAM model performed better than the HEC-HMS model. The NAM model provided acceptable simulations, while the HEC-HMS model did not. Then, we coupled the calculated results of the NAM model with an empirically based debris flow initiation model to obtain a new integrated cascading disaster modeling system to provide improved disaster preparedness and hazard management. In this case study, we found that the coupled model could correctly predict the occurrence of debris flows. Furthermore, we evaluated the effect of the range of input parameter values on the hydrographical shape of the runoff. We also used the grey relational analysis to conduct a sensitivity analysis of the parameters of the model. This study highlighted the important connections between rainfall, hydrological processes, and debris flow, and it provides a useful prototype model system for operational forecasting of debris flows.

Apical extrusion of intracanal debris using two engine driven and step-back instrumentation techniques: an in-vitro study.

Science.gov (United States)

Kustarci, Alper; Akdemir, Neslihan; Siso, Seyda Herguner; Altunbas, Demet

2008-10-01

The purpose of this study was to compare in-vitro the amount of debris extruded apically from extracted teeth, using K3, Protaper rotary instruments and manual step-back technique. Forty five human single-rooted mandibular premolar teeth were randomly divided into 3 groups. The teeth in 3 groups were instrumented until reaching the working length with K3, Protaper rotary instruments and K-type stainless steel instruments with manual step-back technique, respectively. Debris extruded from the apical foramen was collected into centrifuge tubes and the amount was determined. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests, with P=.05 as the level for statistical significance. Statistically significant difference was observed between K3, Protaper and step-back groups in terms of debris extrusion (PStep-back group had the highest mean debris weight, which was significantly different from the K3 and Protaper groups (Pengine-driven Ni-Ti systems extruded significantly less apical debris than step-back technique. However, Protaper rotary instruments extruded significantly more debris than K3 rotary instruments.

Summary of Disposable Debris Shields (DDS) Analysis for Development of Solid Debris Collection at NIF

International Nuclear Information System (INIS)

Shaughnessy, D.A.; Moody, K.J.; Grant, P.M.; Lewis, L.A.; Hutcheon, I.D.; Lindvall, R.; Gostic, J.M.

2011-01-01

simply falling to the bottom of the chamber. In either case, it was determined that using the DDS, or fielding a debris collector at the chamber wall, was not feasible for solid debris collection at NIF due to the small amount of debris that had been collected. In addition, since the glass shields suffered quite a bit of damage from particles impacting the surface, glass was ruled out as a collection medium.

Design and Fabrication of DebriSat - A Representative LEO Satellite for Improvements to Standard Satellite Breakup Models

Science.gov (United States)

Clark, S.; Dietrich, A.; Fitz-Coy, N.; Weremeyer, M.; Liou, J.-C.

2012-01-01

This paper discusses the design and fabrication of DebriSat, a 50 kg satellite developed to be representative of a modern low Earth orbit satellite in terms of its components, materials used, and fabrication procedures. DebriSat will be the target of a future hypervelocity impact experiment to determine the physical characteristics of debris generated after an on-orbit collision of a modern LEO satellite. The major ground-based satellite impact experiment used by DoD and NASA in their development of satellite breakup models was SOCIT, conducted in 1992. The target used for that experiment was a Navy transit satellite (40 cm, 35 kg) fabricated in the 1960's. Modern satellites are very different in materials and construction techniques than those built 40 years ago. Therefore, there is a need to conduct a similar experiment using a modern target satellite to improve the fidelity of the satellite breakup models. To ensure that DebriSat is truly representative of typical LEO missions, a comprehensive study of historical LEO satellite designs and missions within the past 15 years for satellites ranging from 1 kg to 5000 kg was conducted. This study identified modern trends in hardware, material, and construction practices utilized in recent LEO missions. Although DebriSat is an engineering model, specific attention is placed on the quality, type, and quantity of the materials used in its fabrication to ensure the integrity of the outcome. With the exception of software, all other aspects of the satellite s design, fabrication, and assembly integration and testing will be as rigorous as that of an actual flight vehicle. For example, to simulate survivability of launch loads, DebriSat will be subjected to a vibration test. As well, the satellite will undergo thermal vacuum tests to verify that the components and overall systems meet typical environmental standards. Proper assembly and integration techniques will involve comprehensive joint analysis, including the precise

Unmelted meteoritic debris in the Late Pliocene iridium anomaly - Evidence for the ocean impact of a nonchondritic asteroid

Science.gov (United States)

Kyte, F. T.; Brownlee, D. E.

1985-01-01

Ir-bearing particles have been recovered from two piston cores in the Antarctic Basin in the southeastern Pacific. In core E13-3, the particles closely correspond to the Late Pliocene Ir anomaly and have a fluence of about 100 mg/cm sq. In core E13-4, 120 km to the southwest, the particle fluence is about 4 mg/cm sq. Particles with diameters from 0.5 to 4 mm contain at least 35 percent of the Ir in this horizon. Three types of particles have been identified: (1) vesicular, (2) basaltic, and (3) metal. The vesicular particles appear to be shock-melted debris derived from the oceanic impact of a howarditic asteroid containing a minor metal component. These particles have recrystallized from a melt and impact into the ocean has resulted in the incorporation of Na, K, Cl, and radiogenic Sr from the ocean water target. The basaltic clasts appear to be unmelted fragments of the original asteroid which may have separated from the main body prior to impact. Combined vesicular and basaltic particles are believed to have formed by collisions in the debris cloud. Estimates of the diameter of the projectile range from 100 to 500 m. By many orders of magnitude, this is the most massive achondrite sampled by a single meteorite fall.

Preliminary Study on the Damping Effect of a Lateral Damping Buffer under a Debris Flow Load

Directory of Open Access Journals (Sweden)

Zheng Lu

2017-02-01

Full Text Available Simulating the impact of debris flows on structures and exploring the feasibility of applying energy dissipation devices or shock isolators to reduce the damage caused by debris flows can make great contribution to the design of disaster prevention structures. In this paper, we propose a new type of device, a lateral damping buffer, to reduce the vulnerability of building structures to debris flows. This lateral damping buffer has two mechanisms of damage mitigation: when debris flows impact on a building, it acts as a buffer, and when the structure vibrates due to the impact, it acts as a shock absorber, which can reduce the maximum acceleration response and subsequent vibration respectively. To study the effectiveness of such a lateral damping buffer, an impact test is conducted, which mainly involves a lateral damping buffer attached to a two-degree-of-freedom structure under a simulated debris flow load. To enable the numerical study, the equation of motion of the structure along with the lateral damping buffer is derived. A subsequent parametric study is performed to optimize the lateral damping buffer. Finally, a practical design procedure is also provided.

The Fifteen-Year Attitude History of the Wide Field Planetary Camera 2 Radiator and Collection Efficiencies for Micrometeoroids and Orbital Debris

Science.gov (United States)

Anz-Meador, Phillip D.; Liou, Jer-Chyi; Cooke, William J.; Koehler, H.

2010-01-01

An examination of the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC-2) radiator assembly was conducted at NASA Goddard Space Flight Center (GSFC) during the summer of 2009. Immediately apparent was a distinct biasing of the largest 45 impact features towards one side of the radiator, in contrast to an approximately uniform distribution of smaller impacts. Such a distribution may be a consequence of the HST s attitude history and pointing requirements for the cold radiator, or of environmental effects, such as an anisotropic distribution of the responsible population in that size regime. Understanding the size-dependent spatial distribution of impact features is essential to the general analysis of these features. We have obtained from GSFC a 15 minute temporal resolution record of the state vector (Earth Centered Inertial position and velocity) and HST attitude, consisting of the orientation of the velocity and HST-sun vectors in HST body coordinates. This paper reviews the actual state vector and attitude history of the radiator in the context of the randomly tumbling plate assumption and assesses the statistical likelihood (or collection efficiency) of the radiator for the micrometeoroid and orbital debris environments. The NASA Marshall Space Flight Center s Meteoroid Environment Model is used to assess the micrometeoroid component. The NASA Orbital Debris Engineering Model (ORDEM) is used to model the orbital debris component. Modeling results are compared with observations of the impact feature spatial distribution, and the relative contribution of each environmental component are examined in detail.

Debris disc constraints on planetesimal formation

Science.gov (United States)

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

2018-02-01

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

Ballistic impact velocity response of carbon fibre reinforced aluminium alloy laminates for aero-engine

Science.gov (United States)

Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.

2017-12-01

Aerospace and other industries use fibre metal laminate composites extensively due to their high specific strength, stiffness and fire resistance, in addition to their capability to be tailored into different forms for specific purposes. The behaviours of such composites under impact loading is another factor to be considered due to the impacts that occur in take-off, landing, during maintenance and operations. The aim of the study is to determine the specific perforation energy and impact strength of the fibre metal laminates of different layering pattern of carbon fibre reinforced aluminium alloy and hybrid laminate composites of carbon fibre and natural fibres (kenaf and flax). The composites are fabricated using the hand lay-up method in a mould with high bonding polymer matrix and compressed by a compression machine, cured at room temperature for one day and post cure in an oven for three hours. The impact tests are conducted using a gun tunnel system with a flat cylindrical bullet fired using a helium gas at a distance of 14 inches to the target. Impact and residual velocity of the projectile are recorded by high speed video camera. Specific perforation energy of carbon fibre reinforced aluminium alloy (CF+AA) for both before and after fire test are higher than the specific perforation energy of the other composites considered before and after fire test respectively. CF +AA before fire test is 55.18% greater than after. The same thing applies to impact strength of the composites where CF +AA before the fire test has the highest percentage of 11.7%, 50.0% and 32.98% as respectively compared to carbon fibre reinforced aluminium alloy (CARALL), carbon fibre reinforced flax aluminium alloy (CAFRALL) and carbon fibre reinforced kenaf aluminium alloy (CAKRALL), and likewise for the composites after fire test. The considered composites in this test can be used in the designated fire zone of an aircraft engine to protect external debris from penetrating the engine

Safe disposal and recycling of water disaster debris in pakistan

International Nuclear Information System (INIS)

Latif, A.

2014-01-01

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

Vadose zone process that control landslide initiation and debris flow propagation

Science.gov (United States)

Sidle, Roy C.

2015-04-01

Advances in the areas of geotechnical engineering, hydrology, mineralogy, geomorphology, geology, and biology have individually advanced our understanding of factors affecting slope stability; however, the interactions among these processes and attributes as they affect the initiation and propagation of landslides and debris flows are not well understood. Here the importance of interactive vadose zone processes is emphasized related to the mechanisms, initiation, mode, and timing of rainfall-initiated landslides that are triggered by positive pore water accretion, loss of soil suction and increase in overburden weight, and long-term cumulative rain water infiltration. Both large- and small-scale preferential flow pathways can both contribute to and mitigate instability, by respectively concentrating and dispersing subsurface flow. These mechanisms are influenced by soil structure, lithology, landforms, and biota. Conditions conducive to landslide initiation by infiltration versus exfiltration are discussed relative to bedrock structure and joints. The effects of rhizosphere processes on slope stability are examined, including root reinforcement of soil mantles, evapotranspiration, and how root structures affect preferential flow paths. At a larger scale, the nexus between hillslope landslides and in-channel debris flows is examined with emphasis on understanding the timing of debris flows relative to chronic and episodic infilling processes, as well as the episodic nature of large rainfall and related stormflow generation in headwater streams. The hydrogeomorphic processes and conditions that determine whether or not landslides immediately mobilize into debris flows is important for predicting the timing and extent of devastating debris flow runout in steep terrain. Given the spatial footprint of individual landslides, it is necessary to assess vadose zone processes at appropriate scales to ascertain impacts on mass wasting phenomena. Articulating the appropriate

GEO Debris and Interplanetary Dust: Fluxes and Charging Behavior

Science.gov (United States)

Graps, A. L.; Green, S. F.; McBride, N. M.; McDonnell, J. A. M.; Drolshagen, G.; Svedhem, H.; Bunte, K. D.

2005-08-01

A population of cosmic dust mixed with a population of man-made debris exists within the Earth's magnetosphere. Measurements of these provide the data samples for studies of the interplanetary dust particles that travel through our magnetosphere from the outside and for studies of the local byproducts of our space endeavours. Even though instruments to detect natural meteoroids and space debris particles have been flown in Low Earth Orbits (LEO) and on interplanetary missions, very little information on the particle environment for Earth orbits above about 600 km altitude have been available. In particular, knowledge about particles smaller than 1 m in the geostationary (GEO) region was largely unknown before GORID. In September 1996, a dust/debris detector: GORID was launched into GEO as a piggyback instrument on the Russian Express-2 telecommunications spacecraft. The instrument began its normal operation in April 1997 and ended its mission in July 2002. The goal of this work was to use GORID's particle data to identify and separate the space debris from the interplanetary dust particles (IDPs) in GEO, to more finely determine the instrument's measurement characteristics and to derive impact fluxes. Here we present some results of that study. We give GORID flux distributions for debris and IDPs and then present intriguing debris clustering features that might be the result of electrostatic fragmentation of the rocket slag particles.

Emissions from the burning of vegetative debris in air curtain destructors.

Science.gov (United States)

Miller, C Andrew; Lemieux, Paul M

2007-08-01

Although air curtain destructors (ACDs) have been used for quite some time to dispose of vegetative debris, relatively little in-depth testing has been conducted to quantify emissions of pollutants other than CO and particulate matter. As part of an effort to prepare for possible use of ACDs to dispose of the enormous volumes of debris generated by Hurricanes Katrina and Rita, the literature on ACD emissions was reviewed to identify potential environmental issues associated with ACD disposal of construction and demolition (C&D) debris. Although no data have been published on emissions from C&D debris combustion in an ACD, a few studies provided information on emissions from the combustion of vegetative debris. These studies are reviewed, and the results compared with studies of open burning of biomass. Combustion of vegetative debris in ACD units results in significantly lower emissions of particulate matter and CO per unit of mass of debris compared with open pile burning. The available data are not sufficient to make general estimates regarding emissions of organic or metal compounds. The highly transient nature of the ACD combustion process, a minimal degree of operational control, and significant variability in debris properties make accurate prediction of ACD emissions impossible in general. Results of scoping tests conducted in preparation for possible in-depth emissions tests demonstrate the challenges associated with sampling ACD emissions and highlight the transient nature of the process. The environmental impacts of widespread use of ACDs for disposal of vegetative debris and their potential use to reduce the volume of C&D debris in future disaster response scenarios remain a considerable gap in understanding the risks associated with debris disposal options.

Orbital debris: a technical assessment

National Research Council Canada - National Science Library

Committee on Space Debris, National Research Council

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

Characterization of Oribtal Debris via Hyper-Velocity Ground-Based Tests

Science.gov (United States)

Cowardin, H.

2015-01-01

Existing DoD and NASA satellite breakup models are based on a key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), which has supported many applications and matched on-orbit events involving older satellite designs reasonably well over the years. In order to update and improve the break-up models and the NASA Size Estimation Model (SEM) for events involving more modern satellite designs, the NASA Orbital Debris Program Office has worked in collaboration with the University of Florida to replicate a hypervelocity impact using a satellite built with modern-day spacecraft materials and construction techniques. The spacecraft, called DebriSat, was intended to be a representative of modern LEO satellites and all major designs decisions were reviewed and approved by subject matter experts at Aerospace Corporation. DebriSat is composed of 7 major subsystems including attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. All fragments down to 2 mm is size will be characterized via material, size, shape, bulk density, and the associated data will be stored in a database for multiple users to access. Laboratory radar and optical measurements will be performed on a subset of fragments to provide a better understanding of the data products from orbital debris acquired from ground-based radars and telescopes. The resulting data analysis from DebriSat will be used to update break-up models and develop the first optical SEM in conjunction with updates into the current NASA SEM. The characterization of the fragmentation will be discussed in the subsequent presentation.

On the effects of solar storms to the decaying orbital space debris

International Nuclear Information System (INIS)

Herdiwijaya, Dhani; Rachman, Abdul

2014-01-01

Any man-made object in Earth's orbit that no longer serves a useful purpose is classified as orbital debris. Debris objects come from a variety of sources. The majority is related to satellite fragmentation. Other major sources of debris are propulsion systems, and fragmentation of spent upper stages, payload and mission related debris. Serious concern about orbital debris has been growing. Knowledge of the future debris environment is important to both satellite designers, and mission planners, who need to know what hazards a satellite might encounter during the course of its mission. Therefore, it is important to know how much debris is in orbit, where it is located, and when it will decay. The debris environment is complex and dynamically evolving. Objects of different shape and size behave differently in orbit. The geoeffectiveness space environments include solar flux at 10.7 cm, solar energetic particles flux or speed, solar wind flow pressure, electric field, and geomagnetic indices. We study the decaying orbital debris from Tracking and Impact Prediction (TIP) messages in conjuction with geoeffectiveness space environments through time epoch correlation. We found that the decaying and reentry orbital debris are triggered by space environment enhancement within at least one week before reentry. It is not necessary a transient or high energetic and severe solar storm events are needed in decaying processes. We propose that the gradual enhancement processes of space environment will cause satellite surface charging due to energetic electron and enhance drag force

On the effects of solar storms to the decaying orbital space debris

Energy Technology Data Exchange (ETDEWEB)

Herdiwijaya, Dhani, E-mail: dhani@as.itb.ac.id [Astronomy Division and Bosscha Observatory, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Ganesha 10, Bandung 40132 (Indonesia); Rachman, Abdul [Space Science Center, National Institute of Aeronautics and Space, Junjunan 133, Bandung 40173 (Indonesia)

2014-03-24

Any man-made object in Earth's orbit that no longer serves a useful purpose is classified as orbital debris. Debris objects come from a variety of sources. The majority is related to satellite fragmentation. Other major sources of debris are propulsion systems, and fragmentation of spent upper stages, payload and mission related debris. Serious concern about orbital debris has been growing. Knowledge of the future debris environment is important to both satellite designers, and mission planners, who need to know what hazards a satellite might encounter during the course of its mission. Therefore, it is important to know how much debris is in orbit, where it is located, and when it will decay. The debris environment is complex and dynamically evolving. Objects of different shape and size behave differently in orbit. The geoeffectiveness space environments include solar flux at 10.7 cm, solar energetic particles flux or speed, solar wind flow pressure, electric field, and geomagnetic indices. We study the decaying orbital debris from Tracking and Impact Prediction (TIP) messages in conjuction with geoeffectiveness space environments through time epoch correlation. We found that the decaying and reentry orbital debris are triggered by space environment enhancement within at least one week before reentry. It is not necessary a transient or high energetic and severe solar storm events are needed in decaying processes. We propose that the gradual enhancement processes of space environment will cause satellite surface charging due to energetic electron and enhance drag force.

Preparations to receive and store the TMI-2 core debris

International Nuclear Information System (INIS)

Ayers, A.L.R. Jr.; Lilburn, B.J. Jr.

1986-01-01

The March 1979 accident at Unit 2 of Three Mile Island Nuclear Power Station (TMI-2) resulted in considerable damage to the core of the reactor. The core debris will be packaged in canisters and transported by rail cask to the Idaho National Engineering Laboratory (INEL) for storage, examination, and preparation for final disposal. A significant part of recovering from the TMI-2 accident involves receiving and storing the TMI-2 core debris canisters at INEL. This paper highlights preparations for receiving the rail cask at INEL, unloading canisters from the cask in the Hot Shop of Test Area North Building 607, and storing/monitoring those canisters in the Water Pit for up to 30 years

A deployable mechanism concept for the collection of small-to-medium-size space debris

Science.gov (United States)

St-Onge, David; Sharf, Inna; Sagnières, Luc; Gosselin, Clément

2018-03-01

Current efforts in active debris removal strategies and mission planning focus on removing the largest, most massive debris. It can be argued, however, that small untrackable debris, specifically those smaller than 5 cm in size, also pose a serious threat. In this work, we propose and analyze a mission to sweep the most crowded Low Earth Orbit with a large cupola device to remove small-to-medium-size debris. The cupola consists of a deployable mechanism expanding more than 25 times its storage size to extend a membrane covering its surface. The membrane is sufficiently stiff to capture most small debris and to slow down the medium-size objects, thus accelerating their fall. An overview of the design of a belt-driven rigid-link mechanism proposed to support the collecting cupola surface is presented, based on our previous work. Because of its large size, the cupola will be subject to significant aerodynamic drag; thus, orbit maintenance analysis is carried out using the DTM-2013 atmospheric density model and it predicts feasible requirements. While in operation, the device will also be subject to numerous hyper-velocity impacts which may significantly perturb its orientation from the desired attitude for debris collection. Thus, another important feature of the proposed debris removal device is a distributed array of flywheels mounted on the cupola for reorienting and stabilizing its attitude during the mission. Analysis using a stochastic modeling framework for hyper-velocity impacts demonstrates that three-axes attitude stabilization is achievable with the flywheels array. MASTER-2009 software is employed to provide relevant data for all debris related estimates, including the debris fluxes for the baseline mission design and for assessment of its expected performance. Space debris removal is a high priority for ensuring sustainability of space and continual launch and operation of man-made space assets. This manuscript presents the first analysis of a small

TMI-2 core debris analytical methods and results

International Nuclear Information System (INIS)

Akers, D.W.; Cook, B.A.

1984-01-01

A series of six grab samples was taken from the debris bed of the TMI-2 core in early September 1983. Five of these samples were sent to the Idaho National Engineering Laboratory for analysis. Presented is the analysis strategy for the samples and some of the data obtained from the early stages of examination of the samples (i.e., particle size-analysis, gamma spectrometry results, and fissile/fertile material analysis)

Plastic debris in the open ocean

KAUST Repository

Cozar, Andres

2014-06-30

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

Plastic debris in the open ocean.

Science.gov (United States)

Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J Ignacio; Irigoien, Xabier; Ubeda, Bárbara; Hernández-León, Santiago; Palma, Alvaro T; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L; Duarte, Carlos M

2014-07-15

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

Plastic debris in the open ocean

Science.gov (United States)

Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J. Ignacio; Irigoien, Xabier; Úbeda, Bárbara; Hernández-León, Santiago; Palma, Álvaro T.; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L.; Duarte, Carlos M.

2014-01-01

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean. PMID:24982135

Woody debris

Science.gov (United States)

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

2000-01-01

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

Baseline for beached marine debris on Sand Island, Midway Atoll

Science.gov (United States)

Ribic, Christine; Seba B. Sheavly,; John Klavitter,

2012-01-01

Baseline measurements were made of the amount and weight of beached marine debris on Sand Island, Midway Atoll, June 2008–July 2010. On 23 surveys, 32,696 total debris objects (identifiable items and pieces) were collected; total weight was 740.4 kg. Seventy-two percent of the total was pieces; 91% of the pieces were made of plastic materials. Pieces were composed primarily of polyethylene and polypropylene. Identifiable items were 28% of the total; 88% of the identifiable items were in the fishing/aquaculture/shipping-related and beverage/household products-related categories. Identifiable items were lowest during April–August, while pieces were at their lowest during June–August. Sites facing the North Pacific Gyre received the most debris and proportionately more pieces. More debris tended to be found on Sand Island when the Subtropical Convergence Zone was closer to the Atoll. This information can be used for potential mitigation and to understand the impacts of large-scale events such as the 2011 Japanese tsunami.

Impacts, risks, and governance of climate engineering

Directory of Open Access Journals (Sweden)

Zhe Liu

2015-09-01

Full Text Available Climate engineering is a potential alternative method to curb global warming, and this discipline has garnered considerable attention from the international scientific community including the Chinese scientists. This manuscript provides an overview of several aspects of climate engineering, including its definition, its potential impacts and risk, and its governance status. The overall conclusion is that China is not yet ready to implement climate engineering. However, it is important for China to continue conducting research on climate engineering, particularly with respect to its feasible application within China, its potential social, economic, and environmental impacts, and possible international governance structures and governing principles, with regard to both experimentation and implementation.

Predicting on-site environmental impacts of municipal engineering works

International Nuclear Information System (INIS)

Gangolells, Marta; Casals, Miquel; Forcada, Núria; Macarulla, Marcel

2014-01-01

The research findings fill a gap in the body of knowledge by presenting an effective way to evaluate the significance of on-site environmental impacts of municipal engineering works prior to the construction stage. First, 42 on-site environmental impacts of municipal engineering works were identified by means of a process-oriented approach. Then, 46 indicators and their corresponding significance limits were determined on the basis of a statistical analysis of 25 new-build and remodelling municipal engineering projects. In order to ensure the objectivity of the assessment process, direct and indirect indicators were always based on quantitative data from the municipal engineering project documents. Finally, two case studies were analysed and found to illustrate the practical use of the proposed model. The model highlights the significant environmental impacts of a particular municipal engineering project prior to the construction stage. Consequently, preventive actions can be planned and implemented during on-site activities. The results of the model also allow a comparison of proposed municipal engineering projects and alternatives with respect to the overall on-site environmental impact and the absolute importance of a particular environmental aspect. These findings are useful within the framework of the environmental impact assessment process, as they help to improve the identification and evaluation of on-site environmental aspects of municipal engineering works. The findings may also be of use to construction companies that are willing to implement an environmental management system or simply wish to improve on-site environmental performance in municipal engineering projects. -- Highlights: • We present a model to predict the environmental impacts of municipal engineering works. • It highlights significant on-site environmental impacts prior to the construction stage. • Findings are useful within the environmental impact assessment process. • They also

Predicting on-site environmental impacts of municipal engineering works

Energy Technology Data Exchange (ETDEWEB)

Gangolells, Marta, E-mail: marta.gangolells@upc.edu; Casals, Miquel, E-mail: miquel.casals@upc.edu; Forcada, Núria, E-mail: nuria.forcada@upc.edu; Macarulla, Marcel, E-mail: marcel.macarulla@upc.edu

2014-01-15

The research findings fill a gap in the body of knowledge by presenting an effective way to evaluate the significance of on-site environmental impacts of municipal engineering works prior to the construction stage. First, 42 on-site environmental impacts of municipal engineering works were identified by means of a process-oriented approach. Then, 46 indicators and their corresponding significance limits were determined on the basis of a statistical analysis of 25 new-build and remodelling municipal engineering projects. In order to ensure the objectivity of the assessment process, direct and indirect indicators were always based on quantitative data from the municipal engineering project documents. Finally, two case studies were analysed and found to illustrate the practical use of the proposed model. The model highlights the significant environmental impacts of a particular municipal engineering project prior to the construction stage. Consequently, preventive actions can be planned and implemented during on-site activities. The results of the model also allow a comparison of proposed municipal engineering projects and alternatives with respect to the overall on-site environmental impact and the absolute importance of a particular environmental aspect. These findings are useful within the framework of the environmental impact assessment process, as they help to improve the identification and evaluation of on-site environmental aspects of municipal engineering works. The findings may also be of use to construction companies that are willing to implement an environmental management system or simply wish to improve on-site environmental performance in municipal engineering projects. -- Highlights: • We present a model to predict the environmental impacts of municipal engineering works. • It highlights significant on-site environmental impacts prior to the construction stage. • Findings are useful within the environmental impact assessment process. • They also

Wholesale debris removal from LEO

Science.gov (United States)

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.

A Brief History of Meteoroid and Orbital Debris Shielding Technology for US Manned Spacecraft

Science.gov (United States)

Bjorkman, Michael D.; Hyde, James L.

2008-01-01

Meteoroid and orbital debris shielding has played an important role from the beginning of manned spaceflight. During the early 60 s, meteoroid protection drove requirements for new meteor and micrometeoroid impact science. Meteoroid protection also stimulated advances in the technology of hypervelocity impact launchers and impact damage assessment methodologies. The first phase of meteoroid shielding assessments closed in the early 70 s with the end of the Apollo program. The second phase of meteoroid protection technology began in the early 80 s when it was determined that there is a manmade Earth orbital debris belt that poses a significant risk to LEO manned spacecraft. The severity of the Earth orbital debris environment has dictated changes in Space Shuttle and ISS operations as well as driven advances in shielding technology and assessment methodologies. A timeline of shielding technology and assessment methodology advances is presented along with a summary of risk assessment results.

Monitoring and modelling of landslide and debris flow impact on transport and building infrasructure in the Carpathians

Science.gov (United States)

Ivanik, Olena; Shevchuk, Viktor; Yahno, Evgen

2016-04-01

Mechanisms and factors of formation of landslide and debris flow processes are examined in terms of model objects in the Carpathians. The study area is within Eastern Carpathians and Transcarpathian depression (Tisa river basin). There were investigated more than 220 stabilized and active landslides. The analysis of water-gravitational processes in this region with complex heterogeneous geological structure confirmed the priority nature of occurrence of structural landslides in rheologically different geological environments, and made it possible to create a new classification of structural landslides and conditions of their formation with the decisive influence of destructive zones. This classification is the basis for constructing geological, physical and mathematical models of landslide slopes, and subsequent modeling of the landslide hazard based on the determination of the stress-strain state of slopes. Under the proposed mathematical model, the examined phenomenon is described as thermoelastic-plastic equilibrium of the isotropic matrix under effect of applied mass (gravitational field of the Earth) and surface efforts, inhomogeneous stationary temperature field. In addition, it is assumed that the Young modulus at each point of the matrix depends on the water saturation. Debris and mudflows in the Carpathians have a stage character, non-stationary and avalanche movements. The territory is prone to be affected by debris and mudflows, due to the geological, geomorphological and climatic conditions. Therefore the main conditions of the mudflow formation are as follows: the presence of the rock destruction products which could be a solid phase of debris mudflow; presence of the enough quantity of the rainfall runoff for the unconsolidated material removal; ruggedness of relief that provides simultaneous movement of the big values of the water-soil mass with the big velocities. The algorithm calculating the mudflow impact on infrastructure objects in Carpathians

Timing of susceptibility to post-fire debris flows in the western USA

Science.gov (United States)

DeGraff, Jerome V.; Cannon, Susan H.; Gartner, Joseph E.

2015-01-01

Watersheds recently burned by wildfires can have an increased susceptibility to debris flow, although little is known about how long this susceptibility persists, and how it changes over time. We here use a compilation of 75 debris-flow response and fire-ignition dates, vegetation and bedrock class, rainfall regime, and initiation process from throughout the western U.S. to address these issues. The great majority (85 percent) of debris flows occurred within the first 12 months following wildfire, with 71 percent within the first six months. Seven percent of the debris flows occurred between 1 and 1.5 years after a fire, or during the second rainy season to impact an area. Within the first 1.5 years following fires, all but one of the debris flows initiated through runoff-dominated processes, and debris flows occurred in similar proportions in forested and non-forested landscapes. Geologic materials affected how long debris-flow activity persisted, and the timing of debris flows varied within different rainfall regimes. A second, later period of increased debris flow susceptibility between 2.2 and 10 years after fires is indicated by the remaining 8 percent of events, which occurred primarily in forested terrains and initiated largely through landslide processes. The short time period between fire and debris-flow response within the first 1.5 years after ignition, and the longer-term response between 2.2 and 10 years after fire, demonstrate the necessity of both rapid and long-term reactions by land managers and emergency-response agencies to mitigate hazards from debris flows from recently burned areas in the western U.S.

Review of the Space Debris Protection Application on ``TIANGONG-1''

Science.gov (United States)

Zhang, Yong; Li, Ming; Han, Zengyao

Meteoroid and orbital debris (M/OD) is the key factor related to the astronaut safety. The long-term manned spacelab generally adopts protection measures to reduce its hypervelocity impact (HVI) risk. This paper presents the engineering application on“Tiangong-1”,the first long-term spacelab in orbit for China.The application includes the M/OD shielding, active avoidance and mitigation. Firstly, the shielding concepts on“Tiangong-1”manned module and radiator are summarized. Two typical Whipple shields respectively with the 70mm and 50mm standoff are separately utilized for the front cone and cylinder pressurized walls. The ballistic limit Equations (BLE) of these two shieldings are achieved through the HVI tests and numerical simulation. The shields provide the resistance capability of space debris particle.Meanwhile, the M/OD risk is assessed by utilizing the MODAOST to predict the probability of penetration (PP) and probability of critical failure (PCF). The assessment shows that the shielding design meets the safety requirement with the PP of 2.09X10 (-3) and the critical cracking PCF of 3.35X10 (-4) . The radiator,the large-scaled component of manned Spacelab, adopts the Ω-shaped tube to improve the HVI resistance capability with the cost of less mass. Secondly, the orbit transfer strategy is designed not only to meet the requirement of the orbit phase of “Shenzhou” spacecraft but also actively avoid the rendezvous with the cataloged debris in orbit. This strategy is validated through the rendezvous and docking missions of “Shenzhou-8” and “Tiangong-1”,“Shenzhou-9”,“Shenzhou-10”. Thirdly, the mitigation and deactivation concepts are introduced by means of reentry simulation of “Tiangong-1” to protect the space environment and reduce the ground casualty. The space debris protection techniques applied on “Tiangong-1” have been broken through with the successful mission of “Tiangong-1”, and these applied techniques provide

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

Science.gov (United States)

Reynolds, R. C.

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

Dynamics of Unusual Debris Flows on Martian Sand Dunes

Science.gov (United States)

Miyamoto, Hideaki; Dohm, James M.; Baker, Victor R.; Beyer, Ross A.; Bourke, Mary

2004-01-01

Gullies that dissect sand dunes in Russell impact crater often display debris flow-like deposits in their distal reaches. The possible range of both the rheological properties and the flow rates are estimated using a numerical simulation code of a Bingham plastic flow to help explain the formation of these features. Our simulated results are best explained by a rapid debris flow. For example, a debris flow with the viscosity of 10(exp 2) Pa s and the yield strength of 10(exp 2) Pa can form the observed deposits with a flow rate of 0.5 cu m/s sustained over several minutes and total discharged water volume on the order of hundreds of cubic meters, which may be produced by melting a surface layer of interstitial ice within the dune deposits to several centimeters depth.

Development of Harpoon System for Capturing Space Debris

Science.gov (United States)

Reed, Jame; Barraclough, Simon

2013-08-01

Active removal of large space debris has been identified as a key activity to control the growth in the debris population and to limit the risk to active satellites. Astrium is developing technologies to enable such a mission, including a harpoon capture system. The harpoon is simple, compact and lightweight. Since the capture is fast (typically barbs to robustly hold the target, a crushable section to absorb excess impact energy, and a tether to connect to the chaser vehicle. The baseline firing system uses compressed gas, although a simpler one-shot system has also been designed. To understand how a harpoon could be applicable to active debris removal an on-ground prototype and test-rig has been developed for trials with real structural elements of satellites and rocket bodies. Testing has demonstrated the feasibility of the concept and this paper describes the results as well as the next steps. A number of design variants are also proposed which could simplify the system design of an ADR mission.

The effects of large beach debris on nesting sea turtles

Science.gov (United States)

Fujisaki, Ikuko; Lamont, Margaret M.

2016-01-01

A field experiment was conducted to understand the effects of large beach debris on sea turtle nesting behavior as well as the effectiveness of large debris removal for habitat restoration. Large natural and anthropogenic debris were removed from one of three sections of a sea turtle nesting beach and distributions of nests and false crawls (non-nesting crawls) in pre- (2011–2012) and post- (2013–2014) removal years in the three sections were compared. The number of nests increased 200% and the number of false crawls increased 55% in the experimental section, whereas a corresponding increase in number of nests and false crawls was not observed in the other two sections where debris removal was not conducted. The proportion of nest and false crawl abundance in all three beach sections was significantly different between pre- and post-removal years. The nesting success, the percent of successful nests in total nesting attempts (number of nests + false crawls), also increased from 24% to 38%; however the magnitude of the increase was comparably small because both the number of nests and false crawls increased, and thus the proportion of the nesting success in the experimental beach in pre- and post-removal years was not significantly different. The substantial increase in sea turtle nesting activities after the removal of large debris indicates that large debris may have an adverse impact on sea turtle nesting behavior. Removal of large debris could be an effective restoration strategy to improve sea turtle nesting.

Detailed debris flow hazard assessment in Andorra: A multidisciplinary approach

Science.gov (United States)

Hürlimann, Marcel; Copons, Ramon; Altimir, Joan

2006-08-01

achieved during the study showed that the collaboration between geologists, geomorphologists, engineers, and decision makers is essential and that only a multidisciplinary approach allows for solving all the problems of such a complex process as debris flows. Finally, we propose that our approach may be applied to other mountainous areas, adapting the hazard matrix to new local conditions.

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

Science.gov (United States)

Chen, Chien-Yuan; Wang, Qun

2017-08-12

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

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

Science.gov (United States)

Herreid, Sam; Pellicciotti, Francesca

2017-04-01

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

The physics of debris flows

Science.gov (United States)

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

The physics of debris flows

Science.gov (United States)

Iverson, R.M.

1997-01-01

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

TMI-2 core debris grab samples: Examination and analysis: Part 1

International Nuclear Information System (INIS)

Akers, D.W.; Carlson, E.R.; Cook, B.A.; Ploger, S.A.; Carlson, J.O.

1986-09-01

Six samples of particulate debris were removed from the TMI-2 core rubble bed during September and October 1983, and five more samples were obtained in March 1984. The samples (up to 174 g each) were obtained at two locations in the core: H8 (center) and E9 (mid-radius). Ten of the eleven samples were examined at the Idaho National Engineering Laboratory to obtain data on the physical and chemical nature of the debris and the postaccident condition of the core. Portions of the samples also were subjected to differential thermal analysis at Rockwell Hanford Operations and metallurgical and chemical examinations at Argonne National Laboratories. This report presents results of the examination of the core debris grab samples, including physical, metallurgical, chemical, and radiochemical analyses. The results indicate that temperatures in the core reached at least 3100 K during the TMI-2 accident, fuel melting and significant mixing of core structural material occurred, and large fractions of some radionuclides (e.g., 90 Sr and 144 Ce) were retained in the core

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

Science.gov (United States)

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

2018-04-01

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

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

Science.gov (United States)

Karacalioglu, Arif Goktug; Stupl, Jan

2016-01-01

The main goal of this study is to examine the impact of new trends in satellite launch activities on the orbital debris environment and collision risk. Starting from the launch of the first artificial satellite in 1957, space borne technology has become an indispensable part of our lives. More than 6,000 satellites have been launched into Earth orbit. Though the annual number of satellites launched stayed flat for many decades, the trend has recently changed. The satellite market has been undergoing a major evolution with new space companies replacing the traditional approach of deploying a few large, complex and costly satellites with an approach to use a multitude of smaller, less complex and cheaper satellites. This new approach creates a sharp increase in the number of satellites and so the historic trends are no longer representative. As a foundation for this study, a scenario for satellite deployments based on the publicly announced future satellite missions has been developed. These constellation-deploying companies include, but are not limited to, Blacksky, CICERO, EROS, Landmapper, Leosat, Northstar, O3b, OmniEarth, OneWeb, Orbcomm, OuterNet, PlanetIQ, Planet Labs, Radarsat, RapidEye Next Generation, Sentinel, Skybox, SpaceX, and Spire. Information such as the annual number of launches, the number of orbital planes to be used by the constellation, as well as apogee, perigee, inclination, spacecraft mass and area were included or approximated. Besides the production of satellites, a widespread ongoing effort to enhance orbital injection capabilities will allow delivery of more spacecraft more accurately into Earth orbits. A long list of companies such as Microcosm, Rocket Lab, Firefly Space Systems, Sierra Nevada Corporation and Arca Space Corporation are developing new launch vehicles dedicated for small satellites. There are other projects which intend to develop interstages with propulsive capabilities which will allow the deployment of satellites into

Fragments and debris generation using a high power pulsed electron beam

International Nuclear Information System (INIS)

Cassany, Bruno; Courchinoux, Roger; Bertron, Isabelle; Malaise, Frederic; Hebert, David

2002-01-01

The high power Laser Megajoule (LMJ) will be constructed at CEA/DAM/CESTA near Bordeaux, in the south west part of France. Among the problems encountered in the LMJ experimental chamber, there is the impact of the debris produced after a laser shot on the silica optical windows. The production of debris as well as the behavior of optical materials under their influence can be simulated and studied with a pulsed electron beam. We present in this paper the first experimental results obtained by this original technique

Autogenic dynamics of debris-flow fans

Science.gov (United States)

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

Derivation of Elastic Stress Concentration Factor Equations for Debris Fretting Flaws in Pressure Tubes of Pressurized Heavy Water Reactors

International Nuclear Information System (INIS)

Kim, Jong Sung; Oh, Young Jin

2014-01-01

If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis

Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

International Nuclear Information System (INIS)

Katayama, Masahide; Takeba, Atsushi; Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa; Kitazawa, Yukihito

2010-01-01

In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

Energy Technology Data Exchange (ETDEWEB)

Katayama, Masahide, E-mail: masahide.katayama@ctc-g.co.jp [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama-shi, Kanagawa 226-8503 (Japan); Takeba, Atsushi [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Kitazawa, Yukihito [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Aero-Engine and Space Operations, IHI Corporation, 3-1-1, Toyosu, Koto-ku, Tokyo 135-8710 (Japan)

2010-10-15

In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

Space debris: modeling and detectability

Science.gov (United States)

Wiedemann, C.; Lorenz, J.; Radtke, J.; Kebschull, C.; Horstmann, A.; Stoll, E.

2017-01-01

High precision orbit determination is required for the detection and removal of space debris. Knowledge of the distribution of debris objects in orbit is necessary for orbit determination by active or passive sensors. The results can be used to investigate the orbits on which objects of a certain size at a certain frequency can be found. The knowledge of the orbital distribution of the objects as well as their properties in accordance with sensor performance models provide the basis for estimating the expected detection rates. Comprehensive modeling of the space debris environment is required for this. This paper provides an overview of the current state of knowledge about the space debris environment. In particular non-cataloged small objects are evaluated. Furthermore, improvements concerning the update of the current space debris model are addressed. The model of the space debris environment is based on the simulation of historical events, such as fragmentations due to explosions and collisions that actually occurred in Earth orbits. The orbital distribution of debris is simulated by propagating the orbits considering all perturbing forces up to a reference epoch. The modeled object population is compared with measured data and validated. The model provides a statistical distribution of space objects, according to their size and number. This distribution is based on the correct consideration of orbital mechanics. This allows for a realistic description of the space debris environment. Subsequently, a realistic prediction can be provided concerning the question, how many pieces of debris can be expected on certain orbits. To validate the model, a software tool has been developed which allows the simulation of the observation behavior of ground-based or space-based sensors. Thus, it is possible to compare the results of published measurement data with simulated detections. This tool can also be used for the simulation of sensor measurement campaigns. It is

Effects of catastrophic floods and debris flows on the sediment retention structure, North Fork Toutle River, Washington

Science.gov (United States)

Denlinger, Roger P.

2012-01-01

The eruption of Mount St. Helens in 1980 produced a debris avalanche that flowed down the upper reaches of the North Fork Toutle River in southwestern Washington, clogging this drainage with sediment. In response to continuous anomalously high sediment flux into the Toutle and Cowlitz Rivers resulting from this avalanche and associated debris flows, the U.S. Army Corps of Engineers completed a Sediment Retention Structure (SRS) on the North Fork Toutle River in May 1989. For one decade, the SRS effectively blocked most of the sediment transport down the Toutle River. In 1999, the sediment level behind the SRS reached the elevation of the spillway base. Since then, a higher percentage of sediment has been passing the SRS and increasing the flood risk in the Cowlitz River. Currently (2012), the dam is filling with sediment at a rate that cannot be sustained for its original design life, and the U.S. Army Corps of Engineers is concerned with the current ability of the SRS to manage floods. This report presents an assessment of the ability of the dam to pass large flows from three types of scenarios (it is assumed that no damage to the spillway will occur). These scenarios are (1) a failure of the debris-avalanche blockage forming Castle Lake that produces a dambreak flood, (2) a debris flow from failure of that blockage, or (3) a debris flow originating in the crater of Mount St. Helens. In each case, the flows are routed down the Toutle River and through the SRS using numerical models on a gridded domain produced from a digital elevation model constructed with existing topography and dam infrastructure. The results of these simulations show that a structurally sound spillway is capable of passing large floods without risk of overtopping the crest of the dam. In addition, large debris flows originating from Castle Lake or the crater of Mount St. Helens never reach the SRS. Instead, debris flows fill the braided channels upstream of the dam and reduce its storage

Detecting debris flows using ground vibrations

Science.gov (United States)

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.

Catastrophic debris flows near Machu Picchu village (Aguas Calientes), Peru

Czech Academy of Sciences Publication Activity Database

Vilímek, V.; Klimeš, Jan; Vlčko, J.; Carreno, R.

2006-01-01

Roč. 50, č. 7 (2006), s. 1041-1052 ISSN 0943-0105 Institutional research plan: CEZ:AV0Z30460519 Keywords : debris flows * Machu Picchu Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.610, year: 2006

Measuring the gypsum content of C&D debris fines.

Science.gov (United States)

Musson, Stephen E; Xu, Qiyong; Townsend, Timothy G

2008-11-01

Construction and demolition (C&D) debris recycling facilities often produce a screened material intended for use as alternative daily cover (ADC) at active landfills or for shaping and grading at closed landfills. This product contains soil and small pieces of wood, concrete, gypsum drywall, shingles and other components of C&D debris. Concerns have been raised over the contribution of gypsum drywall in C&D debris fines to odor problems at landfills where the product is used. To address such concerns, limitations may be placed on the percentage of gypsum (or sulfate) that can occur, and standardized testing procedures are required to permit valid compliance testing. A test procedure was developed for measuring the gypsum content in C&D debris fines. The concentration of sulfate leached in an aqueous solution was used to estimate the initial gypsum content of the sample. The impact of sample size and leaching time were evaluated. Precision and accuracy increased with increasing gypsum content. Results from replicate samples had an average relative standard deviation of 9%. The gypsum content of fines obtained from different facilities in the US varied widely from 1% to over 25%. These variations not only occurred between differing facilities, but within batches produced within a single facility.

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

Science.gov (United States)

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

2017-12-01

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

Microbes on a bottle: substrate, season and geography influence community composition of microbes colonizing marine plastic debris

OpenAIRE

Carter, Dee A.; Oberbeckmann, Sonja; Osborn, A. Mark; Duhaime, Melissa B.

2016-01-01

Plastic debris pervades in our oceans and freshwater systems and the potential ecosystem-level impacts of this anthropogenic litter require urgent evaluation. Microbes readily colonize aquatic plastic debris and members of these biofilm communities are speculated to include pathogenic, toxic, invasive or plastic degrading-species. The influence of plastic-colonizing microorganisms on the fate of plastic debris is largely unknown, as is the role of plastic in selecting for unique microbial com...

Prediction of mass fraction of agglomerated debris in a LWR severe accident

International Nuclear Information System (INIS)

Kudinov, P.; Davydov, M.

2011-01-01

Ex-vessel termination of accident progression in Swedish type Boiling Water Reactors (BWRs) is contingent upon efficacy of melt fragmentation and solidification in a deep pool of water below reactor vessel. When liquid melt reaches the bottom of the pool it can create agglomerated debris and “cake” regions that increase hydraulic resistance of the bed and affect coolability of the bed. This paper discusses development and application of a conservative-mechanistic approach to quantify mass fractions of agglomerated debris. Experimental data from the DEFOR-A (Debris Bed Formation and Agglomeration) tests with high superheat of binary oxidic simulant material melt is used for validation of the methods. Application of the approach to plant accident analysis suggests that melt superheat has less significant influence on agglomeration of the debris than jet penetration depth. The paper also discusses the impact of the uncertainty in the jet disintegration and penetration behavior on the agglomeration mode map. (author)

Progress on establishing guidelines for National Ignition Facility (NIF) experiments to extend debris shield lifetime

International Nuclear Information System (INIS)

Tobin, M.; Eder, D.; Braun, D.; MacGowan, B.

2002-01-01

The survivability of the debris shields on the National Ignition Facility (NIF) are a key factor for the affordable operation of the facility. The improvements required over Nova debris shields are described. Estimates of debris shield lifetimes in the presence of target emissions with 4-8 J/cm 2 laser fluences indicate lifetimes that may contribute unacceptably to operations costs for NIF. We are developing detailed suggested guidance for target and experiment designers for NIF to assist in minimizing the damage to, and therefore the cost of, maintaining NIF debris shields. The guidance suggests a target mass quantity that as particulate on the debris shields (300 mg) may be within current operating budgets. It also suggests the amount of material that should become shrapnel on a shot (10 mg). Finally, it suggests the level of non-volatile residue (NVR) that would threaten the sol-gel coatings on the debris shields (1 μg/cm 2 ). We review the experimentation on the Nova chamber that included measuring quantities of particulate on debris shields by element and capturing shrapnel pieces in aerogel samples mounted in the chamber. We also describe computations of X-ray emissions from a likely NIF target and the associated ablation expected from this X-ray exposure on supporting target hardware. We describe progress in assessing the benefits of a pre-shield and the possible impact on the guidance for target experiments on NIF. Plans for possible experimentation on Omega and other facilities to improve our understanding of target emissions and their impacts are discussed. Our discussion of planned future work provides a forum to invite possible collaboration with the IFE community

Investigation of the structure of debris beds formed from fuel rods fragmentation

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Duc-Hanh; Fichot, Florian; Topin, Vincent, E-mail: vincent.topin@irsn.fr

2017-03-15

This paper is a study of debris beds that can form in the core of a nuclear power plant under severe accident conditions. Such beds are formed of fragments of pellets and cladding remnants, as observed in the TMI-2 core. Many important issues are related with the morphology of those debris beds: are they coolable in case of water injection and how does molten corium progress through them if they are not coolable? The answers to those questions depend on the structure of the debris bed: porosity, number and arrangement of particles. In order to obtain relevant information, a numerical simulation of the formation of the debris bed is proposed. It relies on a granular approach of the type called “Contact Dynamics” to simulate the collapse of debris and their accumulation. Two different schemes of fuel pellet fragmentation are considered and simulations for different degrees of fragmentation of the pellets are performed. The results show that the number of axial cracks on fuel pellets strongly influences the final porosity of the debris bed. Porosities vary between 31% (less coolable cases) and 45% (similar to TMI-2 observations), with a most probable configuration around 41%. The specific surface of the bed is also evaluated. In the last part, a simple model is used to estimate the impact of the variation in geometry of the numeric debris beds on their flow properties. We show that the permeability and passability can vary respectively with a range of 30% and 15% depending on the number of fragment per pellet. The other benefits of the approach are finally discussed. Among them, the possibility to print 3D samples from the calculated images of debris beds appears as a promising perspective to perform experiments with realistic debris beds.

Report on the 4th International Conference on monitoring, simulation, prevention and remediation of dense and debris flows - Debris Flow 2012

Directory of Open Access Journals (Sweden)

Daniele de Wrachien

2012-09-01

Full Text Available Debris and hyper-concentrated flows are amongst the most destructive of all water-related disasters. These hazards are likely to become more frequent and more important in the future due to the effects of the increase in population, urbanization, land subsidence and the impact of climate change. They affect both rural and urban environments, particularly in river basins and in mountain areas. In recent years, they have attracted more and more attention from the scientific and professional communities due to the number of lives lost, and there is growing public concern for the future. New methods and measures are required to cope with debris flow changes and to achieve a harmonious balance between the environment and economic forces.

Spatial and temporal patterns of stranded intertidal marine debris: is there a picture of global change?

Science.gov (United States)

Browne, Mark Anthony; Chapman, M Gee; Thompson, Richard C; Amaral Zettler, Linda A; Jambeck, Jenna; Mallos, Nicholas J

2015-06-16

Floating and stranded marine debris is widespread. Increasing sea levels and altered rainfall, solar radiation, wind speed, waves, and oceanic currents associated with climatic change are likely to transfer more debris from coastal cities into marine and coastal habitats. Marine debris causes economic and ecological impacts, but understanding the scope of these requires quantitative information on spatial patterns and trends in the amounts and types of debris at a global scale. There are very few large-scale programs to measure debris, but many peer-reviewed and published scientific studies of marine debris describe local patterns. Unfortunately, methods of defining debris, sampling, and interpreting patterns in space or time vary considerably among studies, yet if data could be synthesized across studies, a global picture of the problem may be avaliable. We analyzed 104 published scientific papers on marine debris in order to determine how to evaluate this. Although many studies were well designed to answer specific questions, definitions of what constitutes marine debris, the methods used to measure, and the scale of the scope of the studies means that no general picture can emerge from this wealth of data. These problems are detailed to guide future studies and guidelines provided to enable the collection of more comparable data to better manage this growing problem.

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

Science.gov (United States)

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.

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

Science.gov (United States)

Martin, Jeannie Miller

2013-09-15

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

An Ontological Architecture for Orbital Debris Data

OpenAIRE

Rovetto, Robert J.

2017-01-01

The orbital debris problem presents an opportunity for inter-agency and international cooperation toward the mutually beneficial goals of debris prevention, mitigation, remediation, and improved space situational awareness (SSA). Achieving these goals requires sharing orbital debris and other SSA data. Toward this, I present an ontological architecture for the orbital debris domain, taking steps in the creation of an orbital debris ontology (ODO). The purpose of this ontological system is to ...

Colisional Cloud Debris and Propelled Evasive Maneuvers

Science.gov (United States)

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

2017-10-01

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

An artificial neural network application to produce debris source areas of Barla, Besparmak, and Kapi Mountains (NW Taurids, Turkey

Directory of Open Access Journals (Sweden)

M. C. Tunusluoglu

2007-10-01

Full Text Available Various statistical, mathematical and artificial intelligence techniques have been used in the areas of engineering geology, rock engineering and geomorphology for many years. However, among the techniques, artificial neural networks are relatively new approach used in engineering geology in particular. The attractiveness of ANN for the engineering geological problems comes from the information processing characteristics of the system, such as non-linearity, high parallelism, robustness, fault and failure tolerance, learning, ability to handle imprecise and fuzzy information, and their capability to generalize. For this reason, the purposes of the present study are to perform an application of ANN to a engineering geology problem having a very large database and to introduce a new approach to accelerate convergence. For these purposes, an ANN architecture having 5 neurons in one hidden layer was constructed. During the training stages, total 40 000 training cycles were performed and the minimum RMSE values were obtained at approximately 10 000th cycle. At this cycle, the obtained minimum RMSE value is 0.22 for the second training set, while that of value is calculated as 0.064 again for the second test set. Using the trained ANN model at 10 000th cycle for the second random sampling, the debris source area susceptibility map was produced and adjusted. Finally, a potential debris source susceptibility map for the study area was produced. When considering the field observations and existing inventory map, the produced map has a high prediction capacity and it can be used when assessing debris flow hazard mitigation efforts.

Debris Examination Using Ballistic and Radar Integrated Software

Science.gov (United States)

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

Implementation of an Open-Scenario, Long-Term Space Debris Simulation Approach

Science.gov (United States)

Nelson, Bron; Yang Yang, Fan; Carlino, Roberto; Dono Perez, Andres; Faber, Nicolas; Henze, Chris; Karacalioglu, Arif Goktug; O'Toole, Conor; Swenson, Jason; Stupl, Jan

2015-01-01

This paper provides a status update on the implementation of a flexible, long-term space debris simulation approach. The motivation is to build a tool that can assess the long-term impact of various options for debris-remediation, including the LightForce space debris collision avoidance concept that diverts objects using photon pressure [9]. State-of-the-art simulation approaches that assess the long-term development of the debris environment use either completely statistical approaches, or they rely on large time steps on the order of several days if they simulate the positions of single objects over time. They cannot be easily adapted to investigate the impact of specific collision avoidance schemes or de-orbit schemes, because the efficiency of a collision avoidance maneuver can depend on various input parameters, including ground station positions and orbital and physical parameters of the objects involved in close encounters (conjunctions). Furthermore, maneuvers take place on timescales much smaller than days. For example, LightForce only changes the orbit of a certain object (aiming to reduce the probability of collision), but it does not remove entire objects or groups of objects. In the same sense, it is also not straightforward to compare specific de-orbit methods in regard to potential collision risks during a de-orbit maneuver. To gain flexibility in assessing interactions with objects, we implement a simulation that includes every tracked space object in Low Earth Orbit (LEO) and propagates all objects with high precision and variable time-steps as small as one second. It allows the assessment of the (potential) impact of physical or orbital changes to any object. The final goal is to employ a Monte Carlo approach to assess the debris evolution during the simulation time-frame of 100 years and to compare a baseline scenario to debris remediation scenarios or other scenarios of interest. To populate the initial simulation, we use the entire space

A Dynamical System Approach to the Surface Search of Debris from MH370

Science.gov (United States)

Mancho, Ana M.; Garcia-Garrido, V. J.; Wiggins, S.; Mendoza, C.

2015-11-01

The disappearance of Malaysia Airlines flight MH370 on the morning of the 8th of March 2014 is one of the great mysteries of our time. One relevant aspect of this mystery is that not a single piece of debris from the aircraft was found during the intensive surface search carried out in the months following the crash. Difficulties in the search efforts, due to the uncertainty in the plane's final impact point and the time passed since the accident, brought the question on how the debris was scattered in an always moving ocean, for which there were multiple datasets that do not uniquely determined its state. Our approach to this problem is based on dynamical systems tools that identify dynamic barriers and coherent structures governing transport. By combining different ocean data with these mathematical techniques, we are able to assess the spatio-temporal state of the ocean in the priority search area at the time of impact and the following weeks. Using this information we propose a revised search strategy by showing why one might not have expected to find debris in some large search areas targeted by the search services and determining regions where one might have expected impact debris to be located and that have not been subjected to any exploration. This research has been supported by MINECO under grants MTM2014-56392-R and ICMAT Severo Ochoa project SEV-2011-0087 and ONR grant No. N00014- 01-1-0769. Computational support from CESGA is acknowledged.

Debris filtering effectiveness and pressure drop tests of debris resistance-bottom end piece

International Nuclear Information System (INIS)

Chung, Moon Ki; Song, Chul Hwa; Chung, Heung June; Won, Soon Yeun; Cho, Young Ro; Kim, Bok Deuk

1992-03-01

In this final report, described are the test conditions and test procedures for the debris filtering effectiveness and pressure drop tests for developing the Debris Resistance-Bottom End Piece (DR-BEP). And the test results are tabulated for later evaluation. (Author)

Multi-layered foil capture of micrometeoroids and orbital debris in low Earth orbit

Science.gov (United States)

Kearsley, A.; Graham, G.

Much of our knowledge concerning the sub-millimetre orbital debris population that poses a threat to orbiting satellites has been gleaned from examination of surfaces retrieved and subsequently analysed as part of post-flight investigations. The preservation of the hypervelocity impact-derived remnants located on these surfaces is very variable, whether of space debris or micrometeoroid origin. Whilst glass and metallic materials show highly visible impact craters when examined using optical and electron microscopes, complex mixing between the target material and the impacting particle may make unambiguous interpretation of the impactor origin difficult or impossible. Our recent detailed examination of selected multi-layered insulation (MLI) foils from the ISAS Space Flyer Unit (SFU), and our preliminary study of NASA's Trek blanket, exposed on the Mir station, show that these constructions have the potential to preserve abundant residue material of a quality sufficient for detailed analysis. Although there are still limitations on the recognition of certain sources of orbital debris, the foils complement the metal and glass substrates. We suggest that a purpose-built multi-layered foil structure may prove to be extremely effective for rapid collection and unambiguous analysis of impact- derived residues. Such a collector could be used an environmental monitor for ISS, as it would have low mass, high durability, easy deployment, recovery and storage, making it an economically viable and attractive option.

Initiation of Recent Debris Flows on Mount Rainier, Washington: A Climate Warming Signal?

Science.gov (United States)

Copeland, E. A.; Kennard, P.; Nolin, A. W.; Lancaster, S. T.; Grant, G. E.

2008-12-01

The first week of November 2006 an intense rainstorm inundated the Pacific Northwest and triggered debris flows on many large volcanoes in the Cascade Range of Washington and Oregon. At Mount Rainier, Washington, 45.7 cm of rain was recorded in 36 hours; the storm was preceded by a week of light precipitation and moderate temperatures, so that rain fell on nearly-saturated ground with minimal snow cover. The November 2006 storm was exceptional in that it resulted in a 100-year flood and caused an unprecedented six-month closure of Mount Rainier National Park. It also focused inquiry as to whether debris flows from Cascade volcanoes are likely to occur more frequently in the future as glaciers recede due to climate warming, leaving unstable moraines and sediment that can act as initiation sites. We examined the recent history of debris flows from Mount Rainier using aerial photographs and field surveyed debris flow tracks. Prior to 2001, debris flows were recorded in association with rainfall or glacial outburst floods in 4 drainages, but 3 additional drainages were first impacted by debris flows in 2001, 2005, and 2006, respectively. We discovered that most of the recent debris flows initiated as small gullies in unconsolidated material at the edge of fragmented glaciers or areas of permanent snow and ice. Other initiation sites occur on steep-sided un-vegetated moraines. Of the 28 named glaciers on Mount Rainier, debris flows initiated near five glaciers in the exceptional storm of 2006 (Winthrop, Inter, Kautz-Success, Van Trump, Pyramid, and South Tahoma). Less exceptional storms, however, have also produced wide-spread debris flows: in September 2005, 15.3 cm of rain fell in 48 hours on minimal snow cover and caused debris flows in all except 2 of the glacier drainages that initiated in 2006. Debris flows from both storms initiated at elevations of 1980 to 2400 m, traveled 5 to 10 kilometers, and caused significant streambed aggradation. These results suggest a

Active Space Debris Removal System

Directory of Open Access Journals (Sweden)

Gabriele GUERRA

2017-06-01

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

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

Science.gov (United States)

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

2015-12-01

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

Certain aspects of the environmental impact of nuclear power engineering and thermal power engineering

Energy Technology Data Exchange (ETDEWEB)

Malenchenko, A F [AN Belorusskoj SSR, Minsk. Inst. Yadernoj Ehnergetiki

1979-01-01

A review is made of the both environmental impact and hazard to man resulting from nuclear power engineering as compared with those of thermal power engineering. At present, in addition to such criteria, as physical-chemical characteristic of energy sources, their efficiency and accessibility for exploitation, new requirements were substantiated in relation to safety of their utilization for environment. So, one of essential problems of nuclear power engineering development consists in assessment and prediction of radioecological consequence. The analysis and operating experience of more than 1000 reactor/years with no accidents and harm for pupulation show, that in respect to impact on environment and man nuclear power engineering is much more safe in comparison with energy sources using tradidional fossile fuel.

Backwater development by woody debris

Science.gov (United States)

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.

Roads at risk: traffic detours from debris flows in southern Norway

Science.gov (United States)

Meyer, N. K.; Schwanghart, W.; Korup, O.; Nadim, F.

2015-05-01

Globalisation and interregional exchange of people, goods, and services has boosted the importance of and reliance on all kinds of transport networks. The linear structure of road networks is especially sensitive to natural hazards. In southern Norway, steep topography and extreme weather events promote frequent traffic disruption caused by debris flows. Topographic susceptibility and trigger frequency maps serve as input into a hazard appraisal at the scale of first-order catchments to quantify the impact of debris flows on the road network in terms of a failure likelihood of each link connecting two network vertices, e.g. road junctions. We compute total additional traffic loads as a function of traffic volume and excess distance, i.e. the extra length of an alternative path connecting two previously disrupted network vertices using a shortest-path algorithm. Our risk metric of link failure is the total additional annual traffic load, expressed as vehicle kilometres, because of debris-flow-related road closures. We present two scenarios demonstrating the impact of debris flows on the road network and quantify the associated path-failure likelihood between major cities in southern Norway. The scenarios indicate that major routes crossing the central and north-western part of the study area are associated with high link-failure risk. Yet options for detours on major routes are manifold and incur only little additional costs provided that drivers are sufficiently well informed about road closures. Our risk estimates may be of importance to road network managers and transport companies relying on speedy delivery of services and goods.

An In vitro Comparison of Apically Extruded Debris Using Reciproc, ProTaper Universal, Neolix and Hyflex in Curved Canals

Science.gov (United States)

Labbaf, Hossein; Nazari Moghadam, Kiumars; Shahab, Shahriar; Mohammadi Bassir, Mahshid; Fahimi, Mohammad Amin

2017-01-01

Introduction: As a consequence of root canal preparation, dentinal chips, irrigants and pulp remnants are extruded into preradicular space. This phenomenon may lead to post endodontic flare-ups. The purpose of this study was to compare the amount of extruded debris with four endodontic NiTi engine-driven systems. Methods and Materials: Sixty mesiobuccal roots of maxillary molars with 15-30˚ curvature were divided randomly into four groups (n=15). Each group was instrumented up to apical size of 25 using Reciproc, ProTaper Universal, Neolix and Hyflex. Bidistilled water was used as irrigant and extruded debris was collected in pre-weighted Eppendorf tubes. Tubes were stored in incubator for drying the debris. Extruded debris were weighted in electronic microbalance with accuracy of 0.0001 g. The raw data was analyzed with one way analysis of variance (ANOVA) and Tukey’s HSD post hoc test. Level of significance was set at 0.05. Results: The debris extrusion with Reciproc files was significantly higher than the other groups (P<0.05). Hyflex significantly extruded less debris than other files (P<0.05). There was no significant difference between ProTaper Universal and Neolix regarding the amount of extruded debris (P=0.98). Conclusion: All systems extruded debris during the instrumentation. Reciproc system significantly extruded more debris. Caution should be taken when interpreting the results of this study and applying it to the real clinical situation. PMID:28808456

The ugly face of tourism: Marine debris pollution linked to visitation in the southern Great Barrier Reef, Australia.

Science.gov (United States)

Wilson, Scott P; Verlis, Krista M

2017-04-15

Marine debris is one of the most significant issues facing oceans worldwide. The sources of this debris vary depending on proximity to urban centres and the nature of activities within an area. This paper examines the influence of tourism in the southern Great Barrier Reef (GBR), and its contribution to litter levels in the region. By conducting beach debris surveys on occupied and unoccupied islands, this study found that debris was prevalent throughout the region with significant differences in material types between locations. The greatest source of debris from publically accessible islands was tourist-related, with this source also influencing debris loads on nearby uninhabited islands. A focus on debris at Heron Island, showed that sites close to amenities had greater levels of tourist-sourced items like cigarette butts. These findings indicate the contribution of tourists to this problem and that working with operators and managers is needed to minimise visitor impacts. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2013-04-01

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

Residential tornado safe room from commodity wood products – impact and wind pressure testing

Science.gov (United States)

Robert H. Falk; James J. Bridwell; C. Adam Senalik; Marshall Begel

2018-01-01

A tornado safe room is a shelter designed to provide protection during a tornado and is specifically engineered to resist the high wind pressures and debris impact generated by these high wind events. The required performance criteria of these shelters has been established and is found in the International Code Council Standard for the Design and Construction of Storm...

Role of debris cover to control specific ablation of adjoining Batal ...

Indian Academy of Sciences (India)

impact on the socio-economic development of the region (Barnett et al. ... Debris cove- red glaciers are common in many mountain regions ... Here, we attempt to integrate direct field glacio- .... balance was determined by a network of well dis-.

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

Science.gov (United States)

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.

Disaster Debris Recovery Database - Landfills

Data.gov (United States)

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

Disaster Debris Recovery Database - Recovery

Data.gov (United States)

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

Debris-flows scale predictions based on basin spatial parameters calculated from Remote Sensing images in Wenchuan earthquake area

International Nuclear Information System (INIS)

Zhang, Huaizhen; Chi, Tianhe; Liu, Tianyue; Wang, Wei; Yang, Lina; Zhao, Yuan; Shao, Jing; Yao, Xiaojing; Fan, Jianrong

2014-01-01

Debris flow is a common hazard in the Wenchuan earthquake area. Collapse and Landslide Regions (CLR), caused by earthquakes, could be located from Remote Sensing images. CLR are the direct material source regions for debris flow. The Spatial Distribution of Collapse and Landslide Regions (SDCLR) strongly impact debris-flow formation. In order to depict SDCLR, we referred to Strahler's Hypsometric analysis method and developed 3 functional models to depict SDCLR quantitatively. These models mainly depict SDCLR relative to altitude, basin mouth and main gullies of debris flow. We used the integral of functions as the spatial parameters of SDCLR and these parameters were employed during the process of debris-flows scale predictions. Grouping-occurring debris-flows triggered by the rainstorm, which occurred on September 24th 2008 in Beichuan County, Sichuan province China, were selected to build the empirical equations for debris-flows scale predictions. Given the existing data, only debris-flows runout zone parameters (Max. runout distance L and Lateral width B) were estimated in this paper. The results indicate that the predicted results were more accurate when the spatial parameters were used. Accordingly, we suggest spatial parameters of SDCLR should be considered in the process of debris-flows scale prediction and proposed several strategies to prevent debris flow in the future

Multi-Shock Shield Performance at 15 MJ for Catalogued Debris

Science.gov (United States)

Miller, J. E.; Davis, B. A.; Christiansen, E. L.; Lear, D. M.

2015-01-01

While orbital debris of ten centimeters or more are tracked and catalogued, the difficulty of finding and accurately accounting for forces acting on the objects near the ten centimeter threshold results in both uncertainty of their presence and location. These challenges result in difficult decisions for operators balancing potential costly operational approaches with system loss risk. In this paper, the assessment of the feasibility of protecting a spacecraft from this catalogued debris is described using numerical simulations and a test of a multi-shock shield system against a cylindrical projectile impacting normal to the surface with approximately 15 MJ of kinetic energy. The hypervelocity impact test has been conducted at the Arnold Engineering Development Complex (AEDC) with a 598 g projectile at 6.905 km/s on a NASA supplied multi-shock shield. The projectile used is a hollow aluminum and nylon cylinder with an outside diameter of 8.6 cm and length of 10.3 cm. Figure 1 illustrates the multi-shock shield test article, which consisted of five separate bumpers, four of which are fiberglass fabric and one of steel mesh, and two rear walls, each consisting of Kevlar fabric. The overall length of the test article was 2.65 m. The test article was a 5X scaled-up version of a smaller multi-shock shield previously tested using a 1.4 cm diameter aluminum projectile for an inflatable module project. The distances represented by S1 and S1/2 in the figure are 61 cm and 30.5 cm, respectively. Prior to the impact test, hydrodynamic simulations indicated that some enhancement to the standard multi-shock system is needed to address the effects of the cylindrical shape of the projectile. Based on the simulations, a steel mesh bumper has been added to the shield configuration to enhance the fragmentation of the projectile. The AEDC test occurred as planned, and the modified NASA multi-shock shield successfully stopped 598 g projectile using 85.6 kg/m(exp 2). The fifth bumper

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

Science.gov (United States)

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.

Small satellites and space debris issues

Science.gov (United States)

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.

Development of debris-resistant bottom end piece

International Nuclear Information System (INIS)

Sohn, Dong Seong; Lee, Jae Kyung; Hwang, Dae Hyun; Yim, Jung Sik; Song, Kee Nam; Oh, Dong Seok; Im, Hyun Tae

1993-01-01

Debris-related fuel failures has been identified to be one of the major causes of fuel failures recently occured in nuclear power plants. In order to reduce the possibility of debris-related fuel failures, it is necessary to prevent the debris from reaching to fuel rods. In this regard, it is important to develop Debris-Resistant Bottom End Piece. (Author)

Space Debris Elimination (SpaDE)

Data.gov (United States)

National Aeronautics and Space Administration — The amount of debris in low Earth orbit (LEO) has increased rapidly over the last twenty years. This prevalence of debris increases the likelihood of cascading...

Environmental impact assessment of a turboprop engine with the aid of exergy

International Nuclear Information System (INIS)

Atılgan, Ramazan; Turan, Önder; Altuntaş, Önder; Aydın, Hakan; Synylo, Kateryna

2013-01-01

To develop approaches that effectively reduce engine environmental effect of aircrafts, it is necessary to understand the mechanisms that have enabled improvements in thermodynamic efficiency of aircraft engines. In the present work, a turboprop engine used in regional aircrafts that produces 1948 shp and 640 N.m torque is examined using exergo-environmental method. The results show compressor, combustion chamber, gas generator turbine, power turbine and exhaust nozzle create 9%, 69%, 13%, 7%, 2% of total environmental impact of the engine, respectively. According to rates, the compressor and gas turbine can be considered first to improve in case of component related environmental impact. Furthermore, total component related environmental impact for the turboprop engine is found to be 2.26 mPts/s for the constructional phase and 2.34 mPts/s for the operation/maintenance phases. Accordingly, it is suggested that, in order to estimate environmental impact metric of aircrafts, the exergo-environmental analysis can be employed for aircraft propulsion systems. - Highlights: • Evaluating the exergo-environmental aspects of the turboprop engine. • According to exergo-environmental results, the biggest candidate for improving is the combustion chamber. • Specific environmental impact dominates at engine exhaust outlet of the turboprop engine. • Greatest total component related environmental impact is found at the gas generator turbine of the turboprop engine

Man-Made Debris In and From Lunar Orbit

Science.gov (United States)

Johnson, Nicholas L.; McKay, Gordon A. (Technical Monitor)

1999-01-01

During 1966-1976, as part of the first phase of lunar exploration, 29 manned and robotic missions placed more than 40 objects into lunar orbit. Whereas several vehicles later successfully landed on the Moon and/or returned to Earth, others were either abandoned in orbit or intentionally sent to their destruction on the lunar surface. The former now constitute a small population of lunar orbital debris; the latter, including four Lunar Orbiters and four Lunar Module ascent stages, have contributed to nearly 50 lunar sites of man's refuse. Other lunar satellites are known or suspected of having fallen from orbit. Unlike Earth satellite orbital decays and deorbits, lunar satellites impact the lunar surface unscathed by atmospheric burning or melting. Fragmentations of lunar satellites, which would produce clouds of numerous orbital debris, have not yet been detected. The return to lunar orbit in the 1990's by the Hagoromo, Hiten, Clementine, and Lunar Prospector spacecraft and plans for increased lunar exploration early in the 21st century, raise questions of how best to minimize and to dispose of lunar orbital debris. Some of the lessons learned from more than 40 years of Earth orbit exploitation can be applied to the lunar orbital environment. For the near-term, perhaps the most important of these is postmission passivation. Unique solutions, e.g., lunar equatorial dumps, may also prove attractive. However, as with Earth satellites, debris mitigation measures are most effectively adopted early in the concept and design phase, and prevention is less costly than remediation.

Orbital Debris and NASA's Measurement Program

Science.gov (United States)

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.

Space Debris Mitigation CONOPS Development

Science.gov (United States)

2013-06-01

literature search and review a lone article was found with any discussion of it. As with any net, the concept is to catch space debris objects in the net...travel along the track of the orbit and collect debris along its path. The lone article found contends that the idea “does not work”. Bonnal and...100,000 pieces of debris orbiting the planet , [as] NASA estimated -- 2,600 of them more than [four] inches across. [NASA] called the breakup of the

Flow characteristics of counter-current flow in debris bed

International Nuclear Information System (INIS)

Abe, Yutaka; Adachi, Hiromichi

2004-01-01

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

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

KAUST Repository

Bout, B.

2018-04-09

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

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

Science.gov (United States)

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

2010-05-01

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

Radar rainfall estimation for the identification of debris-flow precipitation thresholds

Science.gov (United States)

Marra, Francesco; Nikolopoulos, Efthymios I.; Creutin, Jean-Dominique; Borga, Marco

2014-05-01

variogram) of the triggering rainfall. These results show that weather radar has the potential to effectively increase the accuracy of rainfall thresholds for debris flow occurrence. However, these benefits may only be achieved if the same monitoring instrumentation is used both to derive the rainfall thresholds and for use of thresholds for real-time identification of debris flows occurrence. References Nikolopoulos, E.I., Borga M., Crema S., Marchi L, Marra F. & Guzzetti F., 2014. Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris-flow occurrence. Geomorphology (conditionally accepted) Peruccacci, S., Brunetti, M.T., Luciani, S., Vennari, C., and Guzzetti, F., 2012. Lithological and seasonal control of rainfall thresholds for the possible initiation of landslides in central Italy, Geomorphology, 139-140, 79-90, 2012.

Global analysis of anthropogenic debris ingestion by sea turtles.

Science.gov (United States)

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

2014-02-01

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

Debris flows: behavior and hazard assessment

Science.gov (United States)

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.

Thermal-hydraulic and characteristic models for packed debris beds

International Nuclear Information System (INIS)

Mueller, G.E.; Sozer, A.

1986-12-01

APRIL is a mechanistic core-wide meltdown and debris relocation computer code for Boiling Water Reactor (BWR) severe accident analyses. The capabilities of the code continue to be increased by the improvement of existing models. This report contains information on theory and models for degraded core packed debris beds. The models, when incorporated into APRIL, will provide new and improved capabilities in predicting BWR debris bed coolability characteristics. These models will allow for a more mechanistic treatment in calculating temperatures in the fluid and solid phases in the debris bed, in determining debris bed dryout, debris bed quenching from either top-flooding or bottom-flooding, single and two-phase pressure drops across the debris bed, debris bed porosity, and in finding the minimum fluidization mass velocity. The inclusion of these models in a debris bed computer module will permit a more accurate prediction of the coolability characteristics of the debris bed and therefore reduce some of the uncertainties in assessing the severe accident characteristics for BWR application. Some of the debris bed theoretical models have been used to develop a FORTRAN 77 subroutine module called DEBRIS. DEBRIS is a driver program that calls other subroutines to analyze the thermal characteristics of a packed debris bed. Fortran 77 listings of each subroutine are provided in the appendix

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

Science.gov (United States)

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...

Using the Data From Accidents and Natural Disasters to Improve Marine Debris Modeling

Science.gov (United States)

Maximenko, N. A.; Hafner, J.; MacFadyen, A.; Kamachi, M.; Murray, C. C.

2016-02-01

In the absence of satisfactory marine debris observing system, drift models provide a unique tool that can be used to identify main pathways and accumulation areas of the natural and anthropogenic debris, including the plastic pollution having increasing impact on the environment and raising concern of the society. Main problems, limiting the utility of model simulations, include the lack of accurate information on distribution, timing, strength and composition of sources of marine debris and the complexity of the hydrodynamics of an object, floating on the surface of a rough sea. To calculate the drift, commonly, models estimate surface currents first and then add the object motion relative to the water. Importantly, ocean surface velocity can't be measured with the existing instruments. For various applications it is derived from subsurface (such as 15-meter drifter trajectories) and satellite (altimetry, scatterometry) data using simple theories (geostrophy, Ekman spiral, etc.). Similarly, even the best ocean general circulation models (OGCM's), utilizing different parameterizations of the mixed layer, significantly disagree on the ocean surface velocities. Understanding debris motion under the direct wind force and in interaction with the breaking wind waves seems to be a task of even greater complexity. In this presentation, we demonstrate how the data of documented natural disasters (such as tsunamis, hurricanes and floods) and other accidents generating marine debris with known times and coordinates of start and/or end points of the trajectories, can be used to calibrate drift models and obtain meaningful quantitative results that can be generalized for other sources of debris and used to plan the future marine debris observing system. On these examples we also demonstrate how the oceanic and atmospheric circulations couple together to determine the pathways and destination areas of different types of the floating marine debris.

TMI-2 core debris analysis

International Nuclear Information System (INIS)

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

1985-01-01

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

TRANSPORT CHARACTERISTICS OF SELECTED PWR LOCA GENERATED DEBRIS

International Nuclear Information System (INIS)

MAJI, A. K.; MARSHALL, B.

2000-01-01

In the unlikely event of a Loss of Coolant Accident (LOCA) in a pressurized water reactor (PWR), break jet impingement would dislodge thermal insulation FR-om nearby piping, as well as other materials within the containment, such as paint chips, concrete dust, and fire barrier materials. Steam/water flows induced by the break and by the containment sprays would transport debris to the containment floor. Subsequently, debris would likely transport to and accumulate on the suction sump screens of the emergency core cooling system (ECCS) pumps, thereby potentially degrading ECCS performance and possibly even failing the ECCS. In 1998, the U. S. Nuclear Regulatory Commission (NRC) initiated a generic study (Generic Safety Issue-191) to evaluate the potential for the accumulation of LOCA related debris on the PWR sump screen and the consequent loss of ECCS pump net positive suction head (NPSH). Los Alamos National Laboratory (LANL), supporting the resolution of GSI-191, was tasked with developing a method for estimating debris transport in PWR containments to estimate the quantity of debris that would accumulate on the sump screen for use in plant specific evaluations. The analytical method proposed by LANL, to predict debris transport within the water that would accumulate on the containment floor, is to use computational fluid dynamics (CFD) combined with experimental debris transport data to predict debris transport and accumulation on the screen. CFD simulations of actual plant containment designs would provide flow data for a postulated accident in that plant, e.g., three-dimensional patterns of flow velocities and flow turbulence. Small-scale experiments would determine parameters defining the debris transport characteristics for each type of debris. The containment floor transport methodology will merge debris transport characteristics with CFD results to provide a reasonable and conservative estimate of debris transport within the containment floor pool and

Infiltration performance of engineered surfaces commonly used for distributed stormwater management.

Science.gov (United States)

Valinski, N A; Chandler, D G

2015-09-01

Engineered porous media are commonly used in low impact development (LID) structures to mitigate excess stormwater in urban environments. Differences in infiltrability of these LID systems arise from the wide variety of materials used to create porous surfaces and subsequent maintenance, debris loading, and physical damage. In this study, the infiltration capacity of six common materials was tested by multiple replicate experiments with automated mini-disk infiltrometers. The tested materials included porous asphalt, porous concrete, porous brick pavers, flexible porous pavement, engineered soils, and native soils. Porous asphalt, large porous brick pavers, and curb cutout rain gardens showed the greatest infiltration rates. Most engineered porous pavements and soils performed better than the native silt loam soils. Infiltration performance was found to be related more to site design and environmental factors than material choice. Sediment trap zones in both pavements and engineered soil rain gardens were found to be beneficial to the whole site performance. Winter chloride application had a large negative impact on poured in place concrete, making it a poor choice for heavily salted areas. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

Liou, Jer-Chyi

2012-01-01

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

Scaling up debris-flow experiments on a centrifuge

Science.gov (United States)

Hung, C.; Capart, H.; Crone, T. J.; Grinspum, E.; Hsu, L.; Kaufman, D.; Li, L.; Ling, H.; Reitz, M. D.; Smith, B.; Stark, C. P.

2013-12-01

Boundary forces generated by debris flows can be powerful enough to erode bedrock and cause considerable damage to infrastructure during runout. Formulation of an erosion-rate law for debris flows is therefore a high priority, and it makes sense to build such a law around laboratory experiments. However, running experiments big enough to generate realistic boundary forces is a logistical challenge to say the least [1]. One alternative is to run table-top simulations with unnaturally weak but fast-eroding pseudo-bedrock, another is to extrapolate from micro-erosion of natural substrates driven by unnaturally weak impacts; hybrid-scale experiments have also been conducted [2]. Here we take a different approach in which we scale up granular impact forces by running our experiments under enhanced gravity in a geotechnical centrifuge [3]. Using a 40cm-diameter rotating drum [2] spun at up to 100g, we generate debris flows with an effective depth of over several meters. By varying effective gravity from 1g to 100g we explore the scaling of granular flow forces and the consequent bed and wall erosion rates. The velocity and density structure of these granular flows is monitored using laser sheets, high-speed video, and particle tracking [4], and the progressive erosion of the boundary surfaces is measured by laser scanning. The force structures and their fluctuations within the granular mass and at the boundaries are explored with contact dynamics numerical simulations that mimic the lab experimental conditions [5]. In this presentation we summarize these results and discuss how they can contribute to the formulation of debris-flow erosion law. [1] Major, J. J. (1997), Journal of Geology 105: 345-366, doi:10.1086/515930 [2] Hsu, L. (2010), Ph.D. thesis, University of California, Berkeley [3] Brucks, A., et al (2007), Physical Review E 75, 032301, doi:10.1103/PhysRevE.75.032301 [4] Spinewine, B., et al (2011), Experiments in Fluids 50: 1507-1525, doi: 10.1007/s00348

On the Solar System-Debris Disk Connecction

OpenAIRE

Moro-Martin, Amaya

2007-01-01

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

Energy dissipation by submarine obstacles during landslide impact on reservoir - potentially avoiding catastrophic dam collapse

Science.gov (United States)

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

2017-04-01

Dense geophysical mass flows such as landslides, debris flows and debris avalanches may generate super tsunami waves as they impact water bodies such as the sea, hydraulic reservoirs or mountain lakes. Here, we apply a comprehensive and general two-phase, physical-mathematical mass flow model (Pudasaini, 2012) that consists of non-linear and hyperbolic-parabolic partial differential equations for mass and momentum balances, and present novel, high-resolution simulation results for two-phase flows, as a mixture of solid grains and viscous fluid, impacting fluid reservoirs with obstacles. The simulations demonstrate that due to the presence of different obstacles in the water body, the intense flow-obstacle-interaction dramatically reduces the flow momentum resulting in the rapid energy dissipation around the obstacles. With the increase of obstacle height overtopping decreases but, the deflection and capturing (holding) of solid mass increases. In addition, the submarine solid mass is captured by the multiple obstacles and the moving mass decreases both in amount and speed as each obstacle causes the flow to deflect into two streams and also captures a portion of it. This results in distinct tsunami and submarine flow dynamics with multiple surface water and submarine debris waves. This novel approach can be implemented in open source GIS modelling framework r.avaflow, and be applied in hazard mitigation, prevention and relevant engineering or environmental tasks. This might be in particular for process chains, such as debris impacts in lakes and subsequent overtopping. So, as the complex flow-obstacle-interactions strongly and simultaneously dissipate huge energy at impact such installations potentially avoid great threat against the integrity of the dam. References: Pudasaini, S. P. (2012): A general two-phase debris flow model. J. Geophys. Res. 117, F03010, doi: 10.1029/ 2011JF002186.

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

Science.gov (United States)

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

2015-09-01

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

A dynamical systems perspective on the absence of debris associated with the disappearance of flight MH370

Science.gov (United States)

García-Garrido, V. J.; Mancho, A. M.; Wiggins, S.; Mendoza, C.

2015-07-01

The disappearance of Malaysia Airlines flight MH370 on the morning of the 8 March 2014 is one of the great mysteries of our time. Perhaps the most relevant aspect of this mystery is that not a single piece of debris from the aircraft has been found. Difficulties in the search efforts, due to the uncertainty in the plane's final impact point and the time that has passed since the accident, bring the question on how the debris has scattered in an always moving ocean, for which there are multiple data sets that do not uniquely determine its state. Our approach to this problem is based on the use of Lagrangian Descriptors (LD), a novel mathematical tool coming from dynamical systems theory that identifies dynamic barriers and coherent structures governing transport. By combining publicly available information supplied by different ocean data sources with these mathematical techniques, we are able to assess the spatio-temporal state of the ocean in the priority search area at the time of impact and the following weeks. Using this information we propose a revised search strategy by showing why one might not have expected to find debris in some large search areas targeted by the Australian Maritime Safety Authority (AMSA), and determining regions where one might have expected impact debris to be located and that have not been subjected to any exploration.

Engineering Change Orders and their Impact on DoD Acquisition Contracts

Science.gov (United States)

2017-03-23

Air Force Institute of Technology AFIT Scholar Theses and Dissertations 3-23-2017 Engineering Change Orders and their Impact on DoD Acquisition...administrator of AFIT Scholar. For more information, please contact richard.mansfield@afit.edu. Recommended Citation Cordell, Ian S., " Engineering Change... ENGINEERING CHANGE ORDERS AND THEIR IMPACT ON DOD ACQUISITION CONTRACTS THESIS Ian S. Cordell, Captain, USAF AFIT-ENC

Alpine debris flows triggered by a 28 July 1999 thunderstorm in the central Front Range, Colorado

Science.gov (United States)

Godt, J.W.; Coe, J.A.

2007-01-01

On 28 July 1999, about 480 alpine debris flows were triggered by an afternoon thunderstorm along the Continental Divide in Clear Creek and Summit counties in the central Front Range of Colorado. The thunderstorm produced about 43??mm of rain in 4??h, 35??mm of which fell in the first 2??h. Several debris flows triggered by the storm impacted Interstate Highway 70, U.S. Highway 6, and the Arapahoe Basin ski area. We mapped the debris flows from color aerial photography and inspected many of them in the field. Three processes initiated debris flows. The first process initiated 11% of the debris flows and involved the mobilization of shallow landslides in thick, often well vegetated, colluvium. The second process, which was responsible for 79% of the flows, was the transport of material eroded from steep unvegetated hillslopes via a system of coalescing rills. The third, which has been termed the "firehose effect," initiated 10% of the debris flows and occurred where overland flow became concentrated in steep bedrock channels and scoured debris from talus deposits and the heads of debris fans. These three processes initiated high on steep hillsides (> 30??) in catchments with small contributing areas (runoff and therefore less likely to generate debris flows by the firehose effect or by rilling. The character of the surficial cover and the spatially variable hydrologic response to intense rainfall, rather than a threshold of contributing area and topographic slope, appears to control the initiation process in the high alpine of the Front Range. Because debris flows initiated by rilling and the firehose effect tend to increase in volume as they travel downslope, these debris flows are potentially more hazardous than those initiated by shallow landslides, which tend to deposit material along their paths. ?? 2006 Elsevier B.V. All rights reserved.

NASA Orbital Debris Baseline Populations

Science.gov (United States)

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

2013-01-01

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

New advances for modelling the debris avalanches

Science.gov (United States)

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

2013-04-01

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

Apical extrusion of debris and irrigants using hand and three rotary instrumentation systems − An in vitro study.

Science.gov (United States)

Madhusudhana, Koppolu; Mathew, Vinod Babu; Reddy, Nelaturi Madhusudhan

2010-10-01

Sterilization of the root canal is a prime aim of successful endodontics. The cleaning and shaping of the canal is directed as achieving this goal. The extrusion of apical debris has a deleterious effect on the prognosis of root canal treatment. Several instrument designs and instrumentation techniques have been developed to prevent this. Forty caries free single rooted human mandibular premolar teeth were divided in four groups of ten teeth each. Teeth in each group were instrumented until the working length with rotary ProTaper, K3, Mtwo systems, and hand K-type stainless steel files. Debris and irrigant extruded from the apical foramen were collected into vials and the amounts were quantitatively determined. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests. The results show that all instrumentation techniques produced significant amount of extruded debris and irrigant. The engine-driven nickel-titanium systems showed less apical extrusion of debris and irrigant than manual technique. No statistically significant difference was found between the groups at [P > 0.05]. Maximum apical debris and irrigant extrusion was seen with K-file group and least in the Mtwo group. The use of rotary files and techniques to perform instrumentation does show less extrusion of the debris and irrigant from the apex. This can contribute to more successful endodontic therapy.

Risk assessment reveals high exposure of sea turtles to marine debris in French Mediterranean and metropolitan Atlantic waters

Science.gov (United States)

Darmon, Gaëlle; Miaud, Claude; Claro, Françoise; Doremus, Ghislain; Galgani, François

2017-07-01

Debris impact on marine wildlife has become a major issue of concern. Mainy species have been identified as being threatened by collision, entanglement or ingestion of debris, generally plastics, which constitute the predominant part of the recorded marine debris. Assessing sensitive areas, where exposure to debris are high, is thus crucial, in particular for sea turtles which have been proposed as sentinels of debris levels for the Marine Strategy Framework Directive and for the Unep-MedPol convention. Our objective here was to assess sea turtle exposure to marine debris in the 3 metropolitan French fronts. Using aerial surveys performed in the Channel, the Atlantic and the Mediterranean regions in winter and summer 2011-2012, we evaluated exposure areas and magnitude in terms of spatial overlap, encounter probability and density of surrounding debris at various spatial scales. Major overlapping areas appeared in the Atlantic and Mediterranean fronts, concerning mostly the leatherback and the loggerhead turtles respectively. The probability for individuals to be in contact with debris (around 90% of individuals within a radius of 2 km) and the density of debris surrounding individuals (up to 16 items with a radius of 2 km, 88 items within a radius of 10 km) were very high, whatever the considered spatial scale, especially in the Mediterranean region and during the summer season. The comparison of the observed mean debris density with random distribution suggested that turtles selected debris areas. This may occur if both debris and turtles drift to the same areas due to currents, if turtles meet debris accidentally by selecting high food concentration areas, and/or if turtles actively seek debris out, confounding them with their preys. Various factors such as species-specific foraging strategies or oceanic features which condition the passive diffusion of debris, and sea turtles in part, may explain spatio-temporal variations in sensitive areas. Further research

Debris Flow Risk Management Framework and Risk Analysis in Taiwan, A Preliminary Study

Science.gov (United States)

Tsao, Ting-Chi; Hsu, Wen-Ko; Chiou, Lin-Bin; Cheng, Chin-Tung; Lo, Wen-Chun; Chen, Chen-Yu; Lai, Cheng-Nong; Ju, Jiun-Ping

2010-05-01

Broadly Acceptable. In order to reduce risk, engineering or other mitigation options were suggested for the 3 different categories, and the risk ranking of the 106 creeks based on the F-N curve were provided. Also, with the fatality statistics of each debris flow event from 1990 to 2009 available (including events of Typhoon Morakot), plotting the F-N curve and comparing it with the curve of 1990 to 2008, it was observed that the former was higher than the latter, and both curves were slightly above the suggested upper bond of the F-N curve, which indicating that in the future more resources and governance should be invested to reduce and minimize debris flow risks. Key Words: debris flow, risk management, risk analysis, risk map, F-N curve

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

Science.gov (United States)

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.

Apical extrusion of debris and irrigants using hand and three rotary instrumentation systems- An in vitro study

Directory of Open Access Journals (Sweden)

Koppolu Madhusudhana

2010-01-01

Full Text Available Introduction: Sterilization of the root canal is a prime aim of successful endodontics. The cleaning and shaping of the canal is directed as achieving this goal. The extrusion of apical debris has a deleterious effect on the prognosis of root canal treatment. Several instrument designs and instrumentation techniques have been developed to prevent this. Materials and Methods: Forty caries free single rooted human mandibular premolar teeth were divided in four groups of ten teeth each. Teeth in each group were instrumented until the working length with rotary ProTaper, K3, Mtwo systems, and hand K-type stainless steel files. Debris and irrigant extruded from the apical foramen were collected into vials and the amounts were quantitatively determined. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests. Results: The results show that all instrumentation techniques produced significant amount of extruded debris and irrigant. The engine-driven nickel-titanium systems showed less apical extrusion of debris and irrigant than manual technique. No statistically significant difference was found between the groups at [P > 0.05]. Maximum apical debris and irrigant extrusion was seen with K-file group and least in the Mtwo group. Conclusions: The use of rotary files and techniques to perform instrumentation does show less extrusion of the debris and irrigant from the apex. This can contribute to more successful endodontic therapy.

Apical extrusion of debris and irrigants using hand and three rotary instrumentation systems– An in vitro study

Science.gov (United States)

Madhusudhana, Koppolu; Mathew, Vinod Babu; Reddy, Nelaturi Madhusudhan

2010-01-01

Introduction: Sterilization of the root canal is a prime aim of successful endodontics. The cleaning and shaping of the canal is directed as achieving this goal. The extrusion of apical debris has a deleterious effect on the prognosis of root canal treatment. Several instrument designs and instrumentation techniques have been developed to prevent this. Materials and Methods: Forty caries free single rooted human mandibular premolar teeth were divided in four groups of ten teeth each. Teeth in each group were instrumented until the working length with rotary ProTaper, K3, Mtwo systems, and hand K-type stainless steel files. Debris and irrigant extruded from the apical foramen were collected into vials and the amounts were quantitatively determined. The data obtained were analyzed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests. Results: The results show that all instrumentation techniques produced significant amount of extruded debris and irrigant. The engine-driven nickel-titanium systems showed less apical extrusion of debris and irrigant than manual technique. No statistically significant difference was found between the groups at [P > 0.05]. Maximum apical debris and irrigant extrusion was seen with K-file group and least in the Mtwo group. Conclusions: The use of rotary files and techniques to perform instrumentation does show less extrusion of the debris and irrigant from the apex. This can contribute to more successful endodontic therapy. PMID:22114427

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

Science.gov (United States)

Termini, Donatella

2013-04-01

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

The effect of debris-flow composition on runout distance

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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.

Comparison of the amount of apical debris extrusion associated with different retreatment systems and supplementary file application during retreatment process.

Science.gov (United States)

Çiçek, Ersan; Koçak, Mustafa Murat; Koçak, Sibel; Sağlam, Baran Can

2016-01-01

The type of instrument affects the amount of debris extruded. The aim of this study was to compare the effect of retreatment systems and supplementary file application on the amount of apical debris extrusion. Forty-eight extracted mandibular premolars with a single canal and similar length were selected. The root canals were prepared with the ProTaper Universal system with a torque-controlled engine. The root canals were dried and were obturated using Gutta-percha and sealer. The specimens were randomly divided into four equal groups according to the retreatment procedures (Group 1, Mtwo retreatment files; Group 2, Mtwo retreatment files + Mtwo rotary file #30 supplementary file; Group 3, ProTaper Universal retreatment (PTUR) files; and Group 4, PTUR files + ProTaper F3 supplementary file). The extruded debris during instrumentation were collected into preweighed Eppendorf tubes. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight. Three consecutive weights were obtained for each tube. No statistically significant difference was found in the amount of apically extruded debris between Groups 1 and 3 (P = 0.590). A significant difference was observed between Groups 1 and 2 (P file significantly increased the amount of apically extruded debris.

Impacts of Innovativeness and Attitude on Entrepreneurial Intention: Among Engineering and Non-Engineering Students

Science.gov (United States)

Law, Kris M. Y.; Breznik, Kristijan

2017-01-01

This study attempted to explore the impacts of attitudinal antecedents on students' entrepreneurial intention. Comparisons between students of engineering and non-engineering backgrounds and gender groups were made. Total of 998 students from universities in Hong Kong were surveyed, leading to a number of highlights in the study. First, it is…

Predicting on-site environmental impacts of municipal engineering works

OpenAIRE

Gangolells Solanellas, Marta; Casals Casanova, Miquel; Forcada Matheu, Núria; Macarulla Martí, Marcel

2014-01-01

The research findings fill a gap in the body of knowledge by presenting an effective way to evaluate the significance of on-site environmental impacts of municipal engineering works prior to the construction stage. First, 42 on-site environmental impacts of municipal engineering works were identified by means of a process-oriented approach. Then, 46 indicators and their corresponding significance limits were determined on the basis of a statistical analysis of 25 new-build and remodelling mun...

Understanding sources, sinks, and transport of marine debris

Science.gov (United States)

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.

Zodiac II: Debris Disk Science from a Balloon

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Bryden, Geoffrey; Traub, Wesley; Roberts, Lewis C., Jr.; Bruno, Robin; Unwin, Stephen; Backovsky, Stan; Brugarolas, Paul; Chakrabarti, Supriya; Chen, Pin; Hillenbrand, Lynne;

Impact of the New Optimal Rules for Arbitration of Disputers Relating to Space Debris Controversies

Science.gov (United States)

Force, Melissa K.

2013-09-01

The mechanisms and procedures for settlement of disputes arising from space debris collision damage, such as that suffered by the Russian Cosmos and US Iridium satellites in 2009, are highly political, nonbinding and unpredictable - all of which contributes to the uncertainty that increases the costs of financing and insuring those endeavors that take place in near-Earth space, especially in Low Earth Orbit. Dispute settlement mechanisms can be found in the 1967 Outer Space Treaty, which provides for consultations in cases involving potentially harmful interference with activities of States parties, and in the 1972 Liability Convention which permits but does not require States - not non-governmental entities - to pursue claims in a resolution process that is nonbinding (unless otherwise agreed.) There are soft- law mechanisms to control the growth of space debris, such as the voluntary 2008 United Nations Space Debris Mitigation Guidelines, and international law and the principles of equity and justice generally provide reparation to restore a person, State or organization to the condition which would have existed if damage had not occurred, but only if all agree to a specific tribunal or international court; even then, parties may be bound by the result only if agreed and enforcement of the award internationally remains uncertain. In all, the dispute resolution process for damage resulting from inevitable future damage from space debris collisions is highly unsatisfactory. However, the Administrative Council of the Permanent Court of Arbitration's recently adopted Optional Rules for the Arbitration of Disputes Relating to Outer Space Activities are, as of yet, untested, and this article will provide an overview of the process, explore the ways in which they fill in gaps in the previous patchwork of systems and analyze the benefits and shortcomings of the new Outer Space Optional Rules.

Design of full scale debris washing system

International Nuclear Information System (INIS)

Taylor, M.L.; Dosani, M.A.; Wentz, J.A.; Patkar, A.N.; Barkley, N.P.

1992-01-01

Since 1987, IT Environmental Programs Inc. (ITEP, a subsidiary of International Technology Corporation) in conjunction with EPA/RREL in Cincinnati, Ohio, have been developing and conducting bench scale and pilot scale testing of a transportable debris washing system which can be used on-site for the decontamination of debris. During the initial phase of the debris decontamination project, a series of bench scale tests were performed in the laboratory to assess the ability of the system to remove contaminants from debris and to facilitate selection of the most efficient surfactant solution. Five nonionic, non-toxic, low foaming, surfactant solution (BG-5, MC-2000, LF-330, BB-100, and L-433) were selected for an experimental evaluation to determine their capacity to solubilize and remove contaminants from the surfaces of corroded steel places. The pieces of corroded steel were coated with a heavy grease mixture prepared in the laboratory and these pieces of debris were placed in a bench scale spray tank on a metal tray and subjected in a high-pressure spray for each surfactant solution for 15 minutes. At the end of the spray cycle, The tray was transferred to a second bench scale system, a high-turbulence wash tank, where the debris was washed for 30 minutes with the same surfactant solution as the used in the spray tank. After the was cycle was completed, the tray was removed from the wash tank and the debris was allowed to air-dry. Before and after treatment, surface-wipe samples were obtained from each of the six pieces of debris and were analyzed for oil and graese. Based on the results, BG-5 was selected as the solution best suited for cleaning grease-laden, metallic debris. 2 refs

Debris flow impact assessment along the Al-Raith Road, Kingdom of Saudi Arabia, using remote sensing data and field investigations

Directory of Open Access Journals (Sweden)

Ahmed M. Youssef

2016-03-01

Full Text Available Jizan mountainous areas in Kingdom of Saudi Arabia are suffering from a variety of slope failures. Most of these failures happen due to heavy rainfalls from time to time. These landslides include rock topples, rockslides, debris flow, and some combination of these which affected many roads, highways, and buildings. The Al-Raith Road is one of these roads connecting Red Sea coast cities with Asir and Al-Hasher areas. The length of this road reaches about 45 km and it has been exposed to landslides during each heavy rain storm. One of these events happened in 24 August 2013, which caused huge debris flows that cut and damaged the road. The current research aims to evaluate the debris flow assessment along this highway using remote sensing data and field studies. According to the detailed analysis of geological and geomorphological maps, as well as field investigation, it is evident that the debris flow materials are mainly related to the different types of landslides. These landslides included rock topples which are frequently observed along the side walls of the channels (flexture which occur in foliated rocks and block which occurs in massive rocks, rock sliding (planner failures where many rock joints and shear zones dip towards the channel, and rockfalls. Debris range in their size from up to 2 m in diameter to fine materials less than 2 mm. These materials can be easily moved with water causing a risk to vehicles, roads, and housing in the area. Field study indicated that these debris channels especially at the lower part have been reactivated several times in the past. Finally, suitable solutions have been suggested to these critical sites to minimize and/or avoid the debris flow hazards in the future.

DebriSat Laboratory Analyses

Science.gov (United States)

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

Collision risk investigation for an operational spacecraft caused by space debris

Science.gov (United States)

Zhang, Binbin; Wang, Zhaokui; Zhang, Yulin

2017-04-01

The collision probability between an operational spacecraft and a population of space debris is investigated. By dividing the 3-dimensional operational space of the spacecraft into several space volume cells (SVC) and proposing a boundary selection method to calculate the collision probability in each SVC, the distribution of the collision risk, as functions of the time, the orbital height, the declination, the impact elevation, the collision velocity, etc., can be obtained. Thus, the collision risk could be carefully evaluated over a time span for the general orbital configurations of the spacecraft and the space debris. As an application, the collision risk for the Tiangong-2 space laboratory caused by the cataloged space debris is discussed and evaluated. Results show that most of the collision threat comes from the front left and front right in Tiangong-2's local, quasi-horizontal plane. And the collision probability will also accumulate when Tiangong-2 moves to the largest declinations (about {±} 42°). As a result, the manned space activities should be avoided at those declinations.

Using Monte Carlo techniques and parallel processing for debris hazard analysis of rocket systems

Energy Technology Data Exchange (ETDEWEB)

LaFarge, R.A.

1994-02-01

Sandia National Laboratories has been involved with rocket systems for many years. Some of these systems have carried high explosive onboard, while others have had FTS for destruction purposes whenever a potential hazard is detected. Recently, Sandia has also been involved with flight tests in which a target vehicle is intentionally destroyed by a projectile. Such endeavors always raise questions about the safety of personnel and the environment in the event of a premature detonation of the explosive or an activation of the FTS, as well as intentional vehicle destruction. Previous attempts to investigate fragmentation hazards for similar configurations have analyzed fragment size and shape in detail but have computed only a limited number of trajectories to determine the probabilities of impact and casualty expectations. A computer program SAFETIE has been written in support of various SNL flight experiments to compute better approximations of the hazards. SAFETIE uses the AMEER trajectory computer code and the Engineering Sciences Center LAN of Sun workstations to determine more realistically the probability of impact for an arbitrary number of exclusion areas. The various debris generation models are described.

Permeability and compression of fibrous porous media generated from dilute suspensions of fiberglass debris during a loss of coolant accident

International Nuclear Information System (INIS)

Lee, Saya; Abdulsattar, Suhaeb S.; Vaghetto, Rodolfo; Hassan, Yassin A.

2015-01-01

Highlights: • Experimental investigation on fibrous debris buildup was conducted. • Head loss through fibrous media was recorded at different approach velocities. • A head loss model through fibrous media was proposed for high porosity (>0.99). • A compression model of fibrous media was developed. - Abstract: Permeability of fibrous porous media has been studied for decades in various engineering applications, including liquid purifications, air filters, and textiles. In nuclear engineering, fiberglass has been found to be a hazard during a Loss-of-Coolant Accident. The high energy steam jet from a break impinges on surrounding fiberglass insulation materials, producing a large amount of fibrous debris. The fibrous debris is then transported through the reactor containment and reaches the sump strainers. Accumulation of such debris on the surface of the strainers produces a fibrous bed, which is a fibrous porous medium that can undermine reactor core cooling. The present study investigated the buildup of fibrous porous media on two types of perforated plate and the pressure drop through the fibrous porous media without chemical effect. The development of the fibrous bed was visually recorded in order to correlate the pressure drop, the approach velocity, and the thickness of the fibrous porous media. The experimental results were compared to semi-theoretical models and theoretical models proposed by other researchers. Additionally, a compression model was developed to predict the thickness and the local porosity of a fibrous bed as a function of pressure

On the Fate of Debris Associated with the Disappearance of Flight MH370: a Dynamical System Perspective

Science.gov (United States)

Mancho, A. M.; Garcia-Garrido, V. J.; Wiggins, S.; Mendoza, C.

2015-12-01

The disappearance of Malaysia Airlines flight MH370 on the morning of the 8th of March 2014 is one of the great mysteries of our time. One relevant aspect of this mystery is that not a single piece of debris from the aircraft was found during the intensive surface search carried out in the months following the crash. Difficulties in the search efforts were due to the uncertainty in the plane's final impact point and the time passed since the accident and rise the question on how the debris was scattered in an always moving ocean, for which there exist multiple datasets that do not uniquely determine its state. Our approach to this problem is based on dynamical systems tools that identify dynamic barriers and coherent structures governing transport. By combining publicly available information supplied by different ocean data sources with these mathematical techniques, we are able to assess the spatio-temporal state of the ocean in the priority search area at the time of impact and the following weeks. Using this information we propose a revised search strategy by showing why one might not have expected to find debris in some large search areas targeted by the search services and determining regions where one might have expected impact debris to be located and that were not subjected to any exploration. This research has been supported by MINECO under grants MTM2014-56392-R and ICMAT Severo Ochoa project SEV-2011-0087 and ONR grant No. N00014- 01-1-0769. Computational support from CESGA is acknowledged. References [1] V. J. García-Garrido, A. M. Mancho, S. Wiggins, and C. Mendoza. A dynamical systems perspective on the absence of debris associated with the disappearance of flight MH370. Nonlin. Processes Geophys. Discuss., 2,1197-1225, doi:10.5194/npgd-2-1197-2015, 2015

Erosion and deposition on a debris-flow fan

Science.gov (United States)

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. 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 a 2d numerical model of debris-flow fan evolution to explore the key controls on debris-flow routing and topographic

Conceptualizing an economically, legally, and politically viable active debris removal option

Science.gov (United States)

Emanuelli, M.; Federico, G.; Loughman, J.; Prasad, D.; Chow, T.; Rathnasabapathy, M.

2014-11-01

It has become increasingly clear in recent years that the issue of space debris, particularly in low-Earth orbit, can no longer be ignored or simply mitigated. Orbital debris currently threatens safe space flight for both satellites and humans aboard the International Space Station. Additionally, orbital debris might impact Earth upon re-entry, endangering human lives and damaging the environment with toxic materials. In summary, orbital debris seriously jeopardizes the future not only of human presence in space, but also of human safety on Earth. While international efforts to mitigate the current situation and limit the creation of new debris are useful, recent studies predicting debris evolution have indicated that these will not be enough to ensure humanity's access to and use of the near-Earth environment in the long-term. Rather, active debris removal (ADR) must be pursued if we are to continue benefiting from and conducting space activities. While the concept of ADR is not new, it has not yet been implemented. This is not just because of the technical feasibility of such a scheme, but also because of the host of economic, legal/regulatory, and political issues associated with debris remediation. The costs of ADR are not insignificant and, in today's restrictive fiscal climate, are unlikely/to be covered by any single actor. Similarly, ADR concepts bring up many unresolved questions about liability, the protection of proprietary information, safety, and standards. In addition, because of the dual use nature of ADR technologies, any venture will necessarily require political considerations. Despite the many unanswered questions surrounding ADR, it is an endeavor worth pursuing if we are to continue relying on space activities for a variety of critical daily needs and services. Moreover, we cannot ignore the environmental implications that an unsustainable use of space will imply for life on Earth in the long run. This paper aims to explore some of these

Potential impacts of Brayton and Stirling cycle engines

Science.gov (United States)

Heft, R. C.

1980-01-01

Two engine technologies (Brayton cycle and Stirling cycle) are examined for their potential economic impact and fuel utilization. An economic analysis of the expected response of buyers to the attributes of the alternative engines was performed. Hedonic coefficients for vehicle fuel efficiency, performance and size were estimated for domestic cars based upon historical data. The marketplace value of the fuel efficiency enhancement provided by Brayton or Stirling engines was estimated. Under the assumptions of 10 years for plant conversions and 1990 and 1995 as the introduction data for turbine and Stirling engines respectively, the comparative fuel savings and present value of the future savings in fuel costs were estimated.

Photometric Studies of GEO Debris

Science.gov (United States)

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

Treatment technology analysis for mixed waste containers and debris

International Nuclear Information System (INIS)

Gehrke, R.J.; Brown, C.H.; Langton, C.A.; Askew, N.M.; Kan, T.; Schwinkendorf, W.E.

1994-03-01

A team was assembled to develop technology needs and strategies for treatment of mixed waste debris and empty containers in the Department of Energy (DOE) complex, and to determine the advantages and disadvantages of applying the Debris and Empty Container Rules to these wastes. These rules issued by the Environmental Protection Agency (EPA) apply only to the hazardous component of mixed debris. Hazardous debris that is subjected to regulations under the Atomic Energy Act because of its radioactivity (i.e., mixed debris) is also subject to the debris treatment standards. The issue of treating debris per the Resource Conservation and Recovery Act (RCRA) at the same time or in conjunction with decontamination of the radioactive contamination was also addressed. Resolution of this issue requires policy development by DOE Headquarters of de minimis concentrations for radioactivity and release of material to Subtitle D landfills or into the commercial sector. The task team recommends that, since alternate treatment technologies (for the hazardous component) are Best Demonstrated Available Technology (BDAT): (1) funding should focus on demonstration, testing, and evaluation of BDAT on mixed debris, (2) funding should also consider verification of alternative treatments for the decontamination of radioactive debris, and (3) DOE should establish criteria for the recycle/reuse or disposal of treated and decontaminated mixed debris as municipal waste

New Laboratory-Based Satellite Impact Experiments for Breakup Fragment Characterization

Science.gov (United States)

Liou, J.-C.; Fitz-Coy, N.; Dikova, R.; Wilson, M.; Huynh, T.; Sorge, M.; Sheaffer, P.; Opiela, J.; Cowardin, H.; Krisko, P.;

Apparatus for controlling nuclear core debris

Science.gov (United States)

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.

Apparatus for controlling nuclear core debris

International Nuclear Information System (INIS)

Jones, R.D.

1978-01-01

Disclosed is an 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

Debris Flows and Related Phenomena

Science.gov (United States)

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

Analysis of a space debris laser removal system

Science.gov (United States)

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.

Debris prevention system, radiation system, and lithograpic apparatus

NARCIS (Netherlands)

2009-01-01

A debris prevention system is constructed and arranged to prevent debris that emanates from a radiation source from propagating with radiation from the radiation source into or within a lithographic apparatus. The debris prevention system includes an aperture that defines a maximum emission angle of

Assessment and Mitigation of the Proton-Proton Collision Debris Impact on the FCC Triplet

CERN Document Server

Besana, Maria Ilaria; Fartoukh, Stephane; Martin, Roman; Tomás, Rogelio

2016-01-01

The Future Circular hadron Collider (FCC-hh), which is designed to operate at a centre-of-mass energy of 100 TeV and to deliver ambitious targets in terms of both instantaneous and integrated luminosity, poses extreme challenges in terms of machine protection during operation and with respect to long-term damages. Energy deposition studies are a crucial ingredient for its design. One of the relevant radiation sources are collision debris particles, which de- posit their energy in the interaction region elements and in particular in the superconducting magnet coils of the final focus triplet quadrupoles, to be protected from the risk of quenching and deterioration. In this contribution, the collision debris will be characterised and expectations obtained with FLUKA will be presented, including magnet lifetime considerations. New techniques including crossing angle gymnastics for peak dose deposition mitigation (as recently introduced in the framework of the LHC operation), will be discussed.

Drone Use in Monioring Open Ocean Surface Debris, Including Paired Manta and Tucker Trawls for Relateing Sea State to Vertical Debris Distribution

Science.gov (United States)

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.

LightForce Photon-Pressure Collision Avoidance: Efficiency Assessment on an Entire Catalogue of Space Debris

Science.gov (United States)

Stupl, Jan Michael; Faber, Nicolas; Foster, Cyrus; Yang Yang, Fan; Levit, Creon

2013-01-01

The potential to perturb debris orbits using photon pressure from ground-based lasers has been confirmed by independent research teams. Two useful applications of this scheme are protecting space assets from impacts with debris and stabilizing the orbital debris environment, both relying on collision avoidance rather than de-orbiting debris. This paper presents the results of a new assessment method to analyze the efficiency of the concept for collision avoidance. Earlier research concluded that one ground based system consisting of a 10 kW class laser, directed by a 1.5 m telescope with adaptive optics, can prevent a significant fraction of debris-debris collisions in low Earth orbit. That research used in-track displacement to measure efficiency and restricted itself to an analysis of a limited number of objects. As orbit prediction error is dependent on debris object properties, a static displacement threshold should be complemented with another measure to assess the efficiency of the scheme. In this paper we present the results of an approach using probability of collision. Using a least-squares fitting method, we improve the quality of the original TLE catalogue in terms of state and co-state accuracy. We then calculate collision probabilities for all the objects in the catalogue. The conjunctions with the highest risk of collision are then engaged by a simulated network of laser ground stations. After those engagements, the perturbed orbits are used to re-assess the collision probability in a 20 minute window around the original conjunction. We then use different criteria to evaluate the utility of the laser-based collision avoidance scheme and assess the number of base-line ground stations needed to mitigate a significant number of high probability conjunctions. Finally, we also give an account how a laser ground station can be used for both orbit deflection and debris tracking.

Problems of Small Debris

Directory of Open Access Journals (Sweden)

V. V. Zelentsov

2015-01-01

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

Earth Satellite Population Instability: Underscoring the Need for Debris Mitigation

Science.gov (United States)

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

2006-01-01

A recent study by NASA indicates that the implementation of international orbital debris mitigation measures alone will not prevent a significant increase in the artificial Earth satellite population, beginning in the second half of this century. Whereas the focus of the aerospace community for the past 25 years has been on the curtailment of the generation of long-lived orbital debris, active remediation of the current orbital debris population should now be reconsidered to help preserve near-Earth space for future generations. In particular, we show in this paper that even if launch operations were to cease today, the population of space debris would continue to grow. Further, proposed remediation techniques do not appear to offer a viable solution. We therefore recommend that, while the aerospace community maintains the current debris-limiting mission regulations and postmission disposal procedures, future emphasis should be placed on finding new remediation technologies for solving this growing problem. Since the launch of Sputnik 1, space activities have created an orbital debris environment that poses increasing impact risks to existing space systems, including human space flight and robotic missions (1, 2). Currently, more than 9,000 Earth orbiting man-made objects (including many breakup fragments), with a combined mass exceeding 5 million kilograms, are tracked by the US Space Surveillance Network and maintained in the US satellite catalog (3-5). Three accidental collisions between cataloged satellites during the period from late 1991 to early 2005 have already been documented (6), although fortunately none resulted in the creation of large, trackable debris clouds. Several studies conducted during 1991-2001 demonstrated, with assumed future launch rates, the unintended growth potential of the Earth satellite population, resulting from random, accidental collisions among resident space objects (7-13). In some low Earth orbit (LEO) altitude regimes where

Construction Site Environmental Impact in Civil Engineering Education

Science.gov (United States)

Teixeira, Jose M. Cardoso

2005-01-01

The environmental impact of construction activity has gained increasing importance in the last few years and become a key subject for civil engineering education. A survey of Portuguese higher education institutions shows that concern with this topic is mostly directed at the impact of large construction projects and especially focused on their…

An integrated approach for hazard assessment and mitigation of debris flows in the Italian Dolomites

Science.gov (United States)

Pasuto, Alessandro; Soldati, Mauro

2004-07-01

This paper shows the results of research on a debris flow occurring on 4 September 1997 in the territory of Cortina d'Ampezzo (Dolomites, Italy) where it caused a significant threat owing to the intense urban development, typical of several Alpine valleys. The event, which affected the talus fans at the foot of Mt. Pomagagnon near the village of Fiames, blocked the state road no. 51 "Alemagna" and, after sparing some houses, barred the course of the Torrent Boite and formed an impoundment. This debris flow aroused great concern among local authorities and the Belluno Civil Engineers Board; therefore, the construction of embankments for protecting the buildings threatened by the debris flow was started immediately. This area was studied in detail during this research in order to identify the hazard situations of the whole slope. The investigations made use of an integrated approach including historical, geomorphological, geostructural, meteorological, pedological, and forest-management aspects. Furthermore, assessments of the debris volumes potentially removable in the source area were carried out. The geomorphological evolution of the area was reconstructed, pinpointing the morphological changes occurring in the past 45 years. Taking into account the increased frequency and magnitude of recent events and considering the location of roads and buildings in the accumulation area, the risk conditions were analysed in order to identify a risk zonation and to propose mitigation measures.

A dynamical systems approach to the surface search for debris associated with the disappearance of flight MH370

Science.gov (United States)

García-Garrido, V. J.; Mancho, A. M.; Wiggins, S.; Mendoza, C.

2015-11-01

The disappearance of Malaysia Airlines flight MH370 on the morning of 8 March 2014 is one of the great mysteries of our time. Perhaps the most relevant aspect of this mystery is that not a single piece of debris from the aircraft was found during the intensive surface search carried out for roughly 2 months following the crash. Difficulties in the search efforts, due to the uncertainty of the plane's final impact point and the time that had passed since the accident, bring the question on how the debris scattered in an always moving ocean, for which there are multiple data sets that do not uniquely determine its state. Our approach to this problem is based on the use of Lagrangian descriptors (LD), a novel mathematical tool coming from dynamical systems theory that identifies dynamic barriers and coherent structures governing transport. By combining publicly available information supplied by different ocean data sources with these mathematical techniques, we are able to assess the spatio-temporal state of the ocean in the priority search area at the time of impact and the following weeks. Using this information we propose a revised search strategy by showing why one might not have expected to find debris in some large search areas targeted by the Australian Maritime Safety Authority (AMSA), and determining regions where one might have expected impact debris to be located, which were not subjected to any exploration.

Heavy metals in recovered fines from construction and demolition debris recycling facilities in Florida.

Science.gov (United States)

Townsend, Timothy; Tolaymat, Thabet; Leo, Kevin; Jambeck, Jenna

2004-10-01

A major product recovered from the processing and recycling of construction and demolition (C&D) debris is screened soil, also referred to as fines. A proposed reuse option for C&D debris fines is fill material, typically in construction projects as a substitute for natural soil. Waste material that is reused in a manner similar to soil must first be characterized to examine potential risks to human health and the environment. In Florida, samples of C&D debris fines from 13 C&D debris recycling facilities were characterized for 11 total and leachable heavy metal concentrations. Total metal concentration results (mg/kg) were compared to existing data on background Florida soil concentrations and to Florida's risk-based soil cleanup target levels (SCTLs). All of the detected metals were found to be elevated with respect to background. The 95% upper confidence level of arsenic from 99 samples was 3.2 mg/kg; arsenic presented the greatest limitation to reuse when compared to the SCTLs. Lead was not found to pose a major problem, likely because of the relatively new building infrastructure in Florida, which results in less demolition debris and less material impacted by lead-based paint. The results of batch leaching tests conducted using simulated rainwater (mg/l) were compared directly to risk-based groundwater levels for Florida and were found not to pose a risk using existing risk assessment policies.

Marine debris ingestion by Magellanic penguins, Spheniscus magellanicus (Aves: Sphenisciformes), from the Brazilian coastal zone.

Science.gov (United States)

Brandão, Martha L; Braga, Karina M; Luque, José L

2011-10-01

Magellanic penguins (Spheniscus magellanicus) are non-breeding winter visitors to the Brazilian coast. In 2008 and 2010, plastic items and other marine debris were found in the stomachs and intestines of 15% of 175 dead penguins collected in the Lagos Region of the state of Rio de Janeiro. One bird had its stomach perforated by a plastic straw, which may have caused its death. There are few records of penguins ingesting plastic litter, but previous studies have found similar levels of debris ingestion among Magellanic penguins stranded on the Brazilian coast (35.8% of 397 birds). The high incidence of marine debris in this species in Brazil may result at least in part from the predominance of juveniles reaching these waters, as juvenile penguins may have a broader diet than adults. It is unclear to what extent plastic ingestion affects the mortality rate in this species and whether the incidence in stranded birds reflects that in the entire population. The present study addresses the increasing impact of plastic debris on marine life. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quantification of marine macro-debris abundance around Vancouver Island, Canada, based on archived aerial photographs processed by projective transformation.

Science.gov (United States)

Kataoka, Tomoya; Murray, Cathryn Clarke; Isobe, Atsuhiko

2017-09-12

The abundance of marine macro-debris was quantified with high spatial resolution by applying an image processing technique to archived shoreline aerial photographs taken over Vancouver Island, Canada. The photographs taken from an airplane at oblique angles were processed by projective transformation for georeferencing, where five reference points were defined by comparing aerial photographs with satellite images of Google Earth. Thereafter, pixels of marine debris were extracted based on their color differences from the background beaches. The debris abundance can be evaluated by the ratio of an area covered by marine debris to that of the beach (percent cover). The horizontal distribution of percent cover of marine debris was successfully computed from 167 aerial photographs and was significantly related to offshore Ekman flows and winds (leeway drift and Stokes drift). Therefore, the estimated percent cover is useful information to determine priority sites for mitigating adverse impacts across broad areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimental study on coolability of particulate core-metal debris bed with oxidization, (2). Fragmentation and enhanced heat transfer in zircaloy debris bed

International Nuclear Information System (INIS)

Su, Guanghui; Sugiyama, Ken-ichiro; Aoki, Hiroomi; Kimura, Iichi

2006-01-01

The oxidization and coolability characteristics of the particulate Zircaloy debris bed, which is deposited under the hard debris and through which first vapor penetrates and then water penetrates, are studied in the present paper. In the vapor penetration experiments, it is found that Zircaloy debris particles are effectively broken into small pieces after making thick oxidized layer with deep clacks by rapid oxidization under the condition that vapor with 20 cm/s penetrates for 30 to 70 min at an initial debris bed temperature of 1,030degC. It is also confirmed in the water penetration experiments that the oxidized particle debris bed has potentially of high coolability when water penetrates through the fully oxidized particle bed because of a high capillary force originating from those particles with deep cracks on their surfaces. Based on the present study, a new scenario for the appearance and disappearance of the hot spot in the TMI-2 accident is possible. The particulate core-metal core-metal debris bed is first heated up by rapid oxidization with heat generation when vapor can penetrate through the debris bed with porosities. This corresponds to the appearance of the hot spot. The resultant oxidized particulate debris bed causes a high coolability due to its high capillary force when the water can touch the debris bed at wet condition. This corresponds to the disappearance of the hot spot. (author)

Debris Avalanches and Debris Flows Transformed from Collapses in the Trans-Mexican Volcanic Belt, México.

Science.gov (United States)

Capra, L.; Macias, J.; Scott, K.; Abrams, M.; Garduño, V.

2001-12-01

Volcanoes of the Trans-Mexican Volcanic Belt (TMVB) have yielded numerous sector and flank collapses during Pleistocene and Holocene time. Sector collapses associated with magmatic activity have yielded debris avalanches with generally limited runout extent (e.g. Popocatépetl, Jocotitlán, and Colima volcanoes). In contrast, flank collapses (smaller failures not involving the volcano summit), both associated and unassociated with magmatic activity and correlated with intense hydrothermal alteration in ice-capped volcanoes, commonly have yielded highly mobile cohesive debris flows (e.g. Pico de Orizaba and Nevado de Toluca volcanoes). Collapse orientation in the TMVB is preferentially to the south and north-east, probably reflecting the tectonic regime of active E-W and NNW faults. The different mobilities of the flows transformed from collapses have important implications for hazard assessment. Both sector and flank collapse can yield highly mobile debris flows, but this transformation is more common in the case of the smaller failures. High mobility is related to factors such as water and clay content of the failed material, the paleotopography, and the extent of entrainment of sediment during flow (bulking). Both debris-avalanches and debris-flows are volcanic hazards that occur from both active volcanoes, as well as those that are inactive or dormant volcanoes, and may by triggered by earthquakes, precipitation, or simple gravity. There will be no precursory warning in such non-volcanic cases.

On the debris-level origins of adhesive wear.

Science.gov (United States)

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

2017-07-25

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

Systems and Sensors for Debris-flow Monitoring and Warning

Directory of Open Access Journals (Sweden)

Lorenzo Marchi

2008-04-01

Full Text Available 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 nonstructural 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

Marine Debris Research, Prevention, and Reduction Act

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Debris Research, Prevention, and Reduction Act legally establishes the National Oceanic and Atmospheric Administration's (NOAA) Marine Debris Program. The...

Disaster Debris Recovery Database - Landfills

Science.gov (United States)

The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

Disaster Debris Recovery Database - Recovery

Science.gov (United States)

The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

Structural debris experiments at operation MILL RACE

International Nuclear Information System (INIS)

Rempel, J.R.; Beck, J.E.; McKee, R.G.

1983-01-01

Structural debris patterns as determined by the mechanisms of building collapse under airblast loading have been studied experimentally at MILL RACE, White Sands, NM. Three near full-size buildings were instrumented to observe deflections, accelerations and air pressures and exposed to two different regimes of incident blast pressure produced by HE simulating 1 kt, viz., 10 and 3 psi; after the shot enough wall debris was located and identified to provide estimates of debris movement. Two of the test buildings were unreinforced, load-bearing masonry, one located at each of the two incident overpressures. The third building was made of reinforced concrete panels and was exposed to approximately 25 psi. Preliminary estimates of the effect of arching on debris energy and distribution are presented

Cetaceans and Marine Debris: The Great Unknown

Directory of Open Access Journals (Sweden)

Mark Peter Simmonds

2012-01-01

Full Text Available Plastics and other marine debris have been found in the gastrointestinal tracts of cetaceans, including instances where large quantities of material have been found that are likely to cause impairment to digestive processes and other examples, where other morbidity and even death have resulted. In some instances, debris may have been ingested as a result of the stranding process and, in others, it may have been ingested when feeding. Those species that are suction or “ram” feeders may be most at risk. There is also evidence of entanglement of cetaceans in marine debris. However, it is usually difficult to distinguish entanglement in active fishing gear from that in lost or discarded gear. The overall significance of the threat from ingested plastics and other debris remains unclear for any population or species of cetaceans, although there are concerns for some taxa, including at the population level, and marine debris in the oceans continues to grow. Further research including the compilation of unpublished material and the investigation of important habitat areas is strongly recommended.

Droplet-Wall/Film Impact in IC Engine Applications

Science.gov (United States)

2017-08-14

Report: Droplet-Wall/ Film Impact in IC Engine Applications (ARO Topic 1.4.1 under ARO’s Dr. Ralph A. Anthenien) The views, opinions and/or findings...Participants: RPPR Final Report as of 12-Oct-2017 Agreement Number: W911NF-16-1-0449 Organization: Princeton University Title: Droplet-Wall/ Film Impact...droplets impacting a wet surface under various film thickness, which plays a critical role in controlling the efficiency of applications such as those

Comparing two models for post-wildfire debris flow susceptibility mapping

Science.gov (United States)

Cramer, J.; Bursik, M. I.; Legorreta Paulin, G.

2017-12-01

Traditionally, probabilistic post-fire debris flow susceptibility mapping has been performed based on the typical method of failure for debris flows/landslides, where slip occurs along a basal shear zone as a result of rainfall infiltration. Recent studies have argued that post-fire debris flows are fundamentally different in their method of initiation, which is not infiltration-driven, but surface runoff-driven. We test these competing models by comparing the accuracy of the susceptibility maps produced by each initiation method. Debris flow susceptibility maps are generated according to each initiation method for a mountainous region of Southern California that recently experienced wildfire and subsequent debris flows. A multiple logistic regression (MLR), which uses the occurrence of past debris flows and the values of environmental parameters, was used to determine the probability of future debris flow occurrence. The independent variables used in the MLR are dependent on the initiation method; for example, depth to slip plane, and shear strength of soil are relevant to the infiltration initiation, but not surface runoff. A post-fire debris flow inventory serves as the standard to compare the two susceptibility maps, and was generated by LiDAR analysis and field based ground-truthing. The amount of overlap between the true locations where debris flow erosion can be documented, and where the MLR predicts high probability of debris flow initiation was statistically quantified. The Figure of Merit in Space (FMS) was used to compare the two models, and the results of the FMS comparison suggest that surface runoff-driven initiation better explains debris flow occurrence. Wildfire can breed conditions that induce debris flows in areas that normally would not be prone to them. Because of this, nearby communities at risk may not be equipped to protect themselves against debris flows. In California, there are just a few months between wildland fire season and the wet

Gender and Health Impacts of Genetically Engineered Crops in ...

International Development Research Centre (IDRC) Digital Library (Canada)

Gender and Health Impacts of Genetically Engineered Crops in Developing Countries ... exists, the gender and health impacts have so far received only cursory attention. ... New funding opportunity for gender equality and climate change ... social inequality, promote greater gender parity, and empower women and girls.

Finite Element Analysis of Saferooms Subjected to Tornado Impact Loads

Science.gov (United States)

Parfilko, Y.; Amaral de Arruda, F.; Varela, B.

2017-10-01

A Tornado is one of the most dreadful and unpredictable events in nature. Unfortunately, weather and geographic conditions make a large portion of the United States prone to this phenomenon. Tornado saferooms are monolithic reinforced concrete protective structures engineered to guard against these natural disasters. Saferooms must withstand impacts and wind loads from EF-5 tornadoes - where the wind speed reaches up to 150 m/s (300 mph) and airborne projectiles can reach up to 50 m/s (100 mph). The objective of this work is to evaluate the performance of a saferoom under impact from tornado-generated debris and tornado-dragged vehicles. Numerical simulations were performed to model the impact problem using explicit dynamics and energy methods. Finite element models of the saferoom, windborne debris, and vehicle models were studied using the LS-DYNA software. RHT concrete material was used to model the saferoom and vehicle models from NCAC were used to characterize damage from impacts at various speeds. Simulation results indicate good performance of the saferoom structure at vehicle impact speeds up to 25 meters per second. Damage is more significant and increases nonlinearly starting at impact velocities of 35 m/s (78 mph). Results of this study give valuable insight into the dynamic response of saferooms subjected to projectile impacts, and provide design considerations for civilian protective structures. Further work is being done to validate the models with experimental measurements.

Molten core debris-sodium interactions: M-Series experiments

International Nuclear Information System (INIS)

Sowa, E.S.; Gabor, J.D.; Pavlik, J.R.; Cassulo, J.C.; Cook, C.J.; Baker, L. Jr.

1979-01-01

Five new kilogram-scale experiments have been carried out. Four of the experiments simulated the situation where molten core debris flows from a breached reactor vessel into a dry reactor cavity and is followed by a flow of sodium (Ex-vessel case) and one experiment simulated the flow of core debris into an existing pool of sodium (In-vessel case). The core debris was closely simulated by a thermite reaction which produced a molten mixture of UO 2 , ZrO 2 , and stainless steel. There was efficient fragmentation of the debris in all experiments with no explosive interactions observed

Numerical simulations on self-leveling behaviors with cylindrical debris bed

Energy Technology Data Exchange (ETDEWEB)

Guo, Liancheng, E-mail: Liancheng.guo@kit.edu [Institute for Nuclear and Energy Technologies (IKET), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Morita, Koji, E-mail: morita@nucl.kyushu-u.ac.jp [Faculty of Engineering, Kyushu University, 2-3-7, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Tobita, Yoshiharu, E-mail: tobita.yoshiharu@jaea.go.jp [Fast Reactor Safety Technology Development Department, Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki 311-1393 (Japan)

2017-04-15

Highlights: • A 3D coupled method was developed by combining DEM with the multi-fluid model of SIMMER-IV code. • The method was validated by performing numerical simulations on a series of experiments with cylindrical particle bed. • Reasonable agreement can demonstrate the applicability of the method in reproducing the self-leveling behavior. • Sensitivity analysis on some model parameters was performed to assess their impacts. - Abstract: The postulated core disruptive accidents (CDAs) are regarded as particular difficulties in the safety analysis of liquid-metal fast reactors (LMFRs). In the CDAs, core debris may settle on the core-support structure and form conic bed mounds. Then debris bed can be levelled by the heat convection and vaporization of surrounding coolant sodium, which is named “self-leveling behavior”. The self-leveling behavior is a crucial issue in the safety analysis, due to its significant effect on the relocation of molten core and heat-removal capability of the debris bed. Considering its complicate multiphase mechanism, a comprehensive computational tool is needed to reasonably simulate transient particle behavior as well as thermal-hydraulic phenomenon of surrounding fluid phases. The SIMMER program is a successful computer code initially developed as an advanced tool for CDA analysis of LMFRs. It is a multi-velocity-field, multiphase, multicomponent, Eulerian, fluid dynamics code coupled with a fuel-pin model and a space- and energy-dependent neutron kinetics model. Until now, the code has been successfully applied in numerical simulations for reproducing key thermal-hydraulic phenomena involved in CDAs as well as performing reactor safety assessment. However, strong interactions between massive solid particles as well as particle characteristics in multiphase flows were not taken into consideration in its fluid-dynamics models. To solve this problem, a new method is developed by combining the discrete element method (DEM

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

Science.gov (United States)

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.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Heavy metals in recovered fines from construction and demolition debris recycling facilities in Florida

International Nuclear Information System (INIS)

Townsend, Timothy; Tolaymat, Thabet; Leo, Kevin; Jambeck, Jenna

2004-01-01

A major product recovered from the processing and recycling of construction and demolition (C and D) debris is screened soil, also referred to as fines. A proposed reuse option for C and D debris fines is fill material, typically in construction projects as a substitute for natural soil. Waste material that is reused in a manner similar to soil must first be characterized to examine potential risks to human health and the environment. In Florida, samples of C and D debris fines from 13 C and D debris recycling facilities were characterized for 11 total and leachable heavy metal concentrations. Total metal concentration results (mg/kg) were compared to existing data on background Florida soil concentrations and to Florida's risk-based soil cleanup target levels (SCTLs). All of the detected metals were found to be elevated with respect to background. The 95% upper confidence level of arsenic from 99 samples was 3.2 mg/kg; arsenic presented the greatest limitation to reuse when compared to the SCTLs. Lead was not found to pose a major problem, likely because of the relatively new building infrastructure in Florida, which results in less demolition debris and less material impacted by lead-based paint. The results of batch leaching tests conducted using simulated rainwater (mg/l) were compared directly to risk-based groundwater levels for Florida and were found not to pose a risk using existing risk assessment policies

Marine debris ingestion by the South American Fur Seal from the Southwest Atlantic Ocean.

Science.gov (United States)

Denuncio, Pablo; Mandiola, María Agustina; Pérez Salles, Sofía Belén; Machado, Rodrigo; Ott, Paulo H; De Oliveira, Larissa Rosa; Rodriguez, Diego

2017-09-15

In this paper, we examined the ingestion of marine debris (MD) in South American fur seals (SAFS), Arctocephalus australis, found dead in coastal beaches of northern Argentina and southern Brazil. Seven percent of 133 SAFS analyzed presented marine debris in their stomach (n=10), with no differences between sampling countries (Brazil n=7, Argentina n=3) and sexes (female=3; male=6). However, significant differences were observed between ages classes, with MD exclusively present in stomach contents of young specimens. Plastics represents 90% of MD ingested by the SAFS, whereas regarding the source, fishery-related items (e.g. monofilament lines) were the main MD (70%), with a lesser proportion of packaging (e.g. pieces of bags). Low numbers but large size pieces of MD were found in each stomach affected. Negative effects on the individuals could not be fully evaluated. Therefore, the potential impacts of the marine debris to the SAFS deserve further elucidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Particulate metallic debris in cemented total hip arthroplasty.

Science.gov (United States)

Salvati, E A; Betts, F; Doty, S B

1993-08-01

Several studies conducted by the authors in the last six years demonstrate that the generation of metallic debris is more severe with titanium alloy than with cobalt-chrome alloy femoral components in cemented total hip arthroplasty (THA). The debris is generated from the articulating surface, particularly if entrapped acrylic debris produces three-body wear, and from the stem surface when the component loosens and abrades against fragmented cement. In selected cases in which the titanium metallic debris is copious, premature failure and severe progressive bone loss occurs. Electron microscopy demonstrates that the particles of metallic debris can be extremely small (a few hundredths of 1 micron). They are phagocytized by the macrophages and transported to the phagolysosomes. In this highly corrosive environment, the very high surface area of the particles may release toxic concentrations of the constituents of the alloy intracellularly, probably leading to progressive cell degeneration and death, with subsequent release of intracellular enzymes and ingested metallic debris. This cycle most likely repeats itself, leading to tissue necrosis. The results presented do not support the use of titanium alloy femoral components for cemented THA, particularly for the articulating surface.

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

International Nuclear Information System (INIS)

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

1994-11-01

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

Alternative fuels in fire debris analysis: biodiesel basics.

Science.gov (United States)

Stauffer, Eric; Byron, Doug

2007-03-01

Alternative fuels are becoming more prominent on the market today and, soon, fire debris analysts will start seeing them in liquid samples or in fire debris samples. Biodiesel fuel is one of the most common alternative fuels and is now readily available in many parts of the United States and around the world. This article introduces biodiesel to fire debris analysts. Biodiesel fuel is manufactured from vegetable oils and/or animal oils/fats. It is composed of fatty acid methyl esters (FAMEs) and is sold pure or as a blend with diesel fuel. When present in fire debris samples, it is recommended to extract the debris using passive headspace concentration on activated charcoal, possibly followed by a solvent extraction. The gas chromatographic analysis of the extract is first carried out with the same program as for regular ignitable liquid residues, and second with a program adapted to the analysis of FAMEs.

Evaluation of Oconee steam-generator debris. Final report

International Nuclear Information System (INIS)

Rigdon, M.A.; Rubright, M.M.; Sarver, L.W.

1981-10-01

Pieces of debris were observed near damaged tubes at the 14th support plate elevation in the Oconee 1-B steam generator. A project was initiated to evaluate the physical and chemical nature of the debris, to identify its source, and to determine its role in tube damage at this elevation. Various laboratory techniques were used to characterize several debris and mill scale samples. Data from these samples were then compared with each other and with literature data. It was concluded that seven of eight debris samples were probably formed in the steam generator. Six of these samples were probably formed by high temperature aqueous corrosion early in the life of the steam generator. The seventh sample was probably formed by the deposition and spalling of magnetite on the Inconel steam generator tubes. None of the debris samples resembled any of the mill scale samples

Engineering women re-visioning women's scientific achievements and impacts

CERN Document Server

Tietjen, Jill S

2017-01-01

Packed with fascinating biographical sketches of female engineers, this chronological history of engineering brightens previously shadowy corners of our increasingly engineered world’s recent past. In addition to a detailed description of the diverse arenas encompassed by the word ‘engineering’ and a nuanced overview of the development of the field, the book includes numerous statistics and thought provoking facts about women’s roles in the achievement of thrilling scientific innovations. This text is a unique resource for students launching research projects in engineering and related fields, professionals interested in gaining a broader understanding of how engineering as a discipline has been impacted by events of global significance, and scholars of women’s immense, often obscured, contributions to scientific progress. Illuminates the many significant contributions of women in engineering Educates readers about the evolution of the field of engineering over the last century Demonstrates how key ...

Ferrographic and spectrometer oil analysis from a failed gas turbine engine

Science.gov (United States)

Jones, W. R., Jr.

1982-01-01

An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph, a plasma, an atomic absorption, and an emission spectrometer to see if this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2 to 0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations ( 2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. The oil analyses eliminated a lubrication system bearing or shaft seal failure as the cause of the engine failure.

Laser Remediation of Threats Posed by Small Orbital Debris

Science.gov (United States)

Fork, Richard L.; Rogers, Jan R.; Hovater, Mary A.

2012-01-01

The continually increasing amount of orbital debris in near Earth space poses an increasing challenge to space situational awareness. Recent collisions of spacecraft caused abrupt increases in the density of both large and small debris in near Earth space. An especially challenging class of threats is that due to the increasing density of small (1 mm to 10 cm dimension) orbital debris. This small debris poses a serious threat since: (1) The high velocity enables even millimeter dimension debris to cause serious damage to vulnerable areas of space assets, e.g., detector windows; (2) The small size and large number of debris elements prevent adequate detection and cataloguing. We have identified solutions to this threat in the form of novel laser systems and novel ways of using these laser systems. While implementation of the solutions we identify is challenging we find approaches offering threat mitigation within time frames and at costs of practical interest. We base our analysis on the unique combination of coherent light specifically structured in both space and time and applied in novel ways entirely within the vacuum of space to deorbiting small debris. We compare and contrast laser based small debris removal strategies using ground based laser systems with strategies using space based laser systems. We find laser systems located and used entirely within space offer essential and decisive advantages over groundbased laser systems.

Loopy, Floppy and Fragmented: Debris Characteristics Matter

Science.gov (United States)

Parrish, J.; Burgess, H. K.

2016-02-01

Marine debris is a world-wide problem threatening the health and safety of marine organisms, ecosystems, and humans. Recent and ongoing research shows that risk of harm is not associated with identity, but rather with a set of specific character states, where the character state space intersection is defined by the organism of interest. For example, intersections of material, color, rigidity and size predict the likelihood of an object being ingested: plastic, clear-white, floppy objects risks to sea turtles whereas yellow-red, rigid objects risks to albatrosses. A character state space approach allows prioritization of prevention and removal of marine debris informed by risk assessments for species of interest by comparing species ranges with spatio-temporal hotspots of all debris with characteristics known to be associated with increased risk of harm, regardless of identity. With this in mind, the Coastal Observation and Seabird Survey Team (COASST) developed and tested a 20 character data collection approach to quantifying the diversity and abundance of marine debris found on beaches. Development resulted in meta-analysis of the literature and expert opinion eliciting harmful character state space. Testing included data collection on inter-rater reliability and accuracy, where the latter included 75 participants quantifying marine debris characteristics on monthly surveys of 30 beaches along the Washington and Oregon coastlines over the past year. Pilot work indicates that characters must be simply and operationally defined, states must be listed, and examples must be provided for color states. Complex characters (e.g., windage, shape) are not replicable across multiple data collectors. Although data collection takes longer than other marine debris surveys for a given amount of debris and area surveyed, volunteer rapidity and accuracy improved within 3-5 surveys. Initial feedback indicated that volunteers were willing to continue collecting data as long as they

The fast debris evolution model

Science.gov (United States)

Lewis, H. G.; Swinerd, G. G.; Newland, R. J.; Saunders, A.

2009-09-01

The 'particles-in-a-box' (PIB) model introduced by Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] removed the need for computer-intensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FADE), employs a first-order differential equation to describe the rate at which new objects ⩾10 cm are added and removed from the environment. Whilst Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FADE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FADE model has been implemented as a client-side, web-based service using JavaScript embedded within a HTML document. Due to the simple nature of the algorithm, FADE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ⩾10 cm LEO debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model

Space Tourism: Orbital Debris Considerations

Science.gov (United States)

Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

2002-01-01

Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a

Changes of Space Debris Orbits After LDR Operation

Science.gov (United States)

Wnuk, E.; Golebiewska, J.; Jacquelard, C.; Haag, H.

2013-09-01

A lot of technical studies are currently developing concepts of active removal of space debris to protect space assets from on orbit collision. For small objects, such concepts include the use of ground-based lasers to remove or reduce the momentum of the objects thereby lowering their orbit in order to facilitate their decay by re-entry into the Earth's atmosphere. The concept of the Laser Debris Removal (LDR) system is the main subject of the CLEANSPACE project. One of the CLEANSPACE objectives is to define a global architecture (including surveillance, identification and tracking) for an innovative ground-based laser solution, which can remove hazardous medium debris around selected space assets. The CLEANSPACE project is realized by a European consortium in the frame of the European Commission Seventh Framework Programme (FP7), Space topic. The use of sequence of laser operations to remove space debris, needs very precise predictions of future space debris orbital positions, on a level even better than 1 meter. Orbit determination, tracking (radar, optical and laser) and orbit prediction have to be performed with accuracy much better than so far. For that, the applied prediction tools have to take into account all perturbation factors that influence object orbit. The expected object's trajectory after the LDR operation is a lowering of its perigee. To prevent the debris with this new trajectory to collide with another object, a precise trajectory prediction after the LDR sequence is therefore the main task allowing also to estimate re-entry parameters. The LDR laser pulses change the debris object velocity v. The future orbit and re-entry parameters of the space debris after the LDR engagement can be calculated if the resulting ?v vector is known with the sufficient accuracy. The value of the ?v may be estimated from the parameters of the LDR station and from the characteristics of the orbital debris. However, usually due to the poor knowledge of the debris

Photometric Studies of GEO Orbital Debris

Science.gov (United States)

Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Ed; 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 Cerro Tololo Inter- American Observatory (CTIO) 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R=15th 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? More than 90 calibrated sequences of R-B-V-I-R magnitudes for a sample of 50 objects 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 the B-R color is a true measure of the surface of the debris piece facing the

Laser ignition of traumatically embedded firework debris.

Science.gov (United States)

Taylor, C R

1998-01-01

The Q-switched ruby laser (QSRL) has a good track record for traumatic tattoo removal. An unusual case of QSRL-treatment of a traumatic tattoo composed of firework debris is presented. A young man's traumatic tattoo, composed of firework debris, underwent QSRL ablation at 4-7 J/cm2 (pulse width 5 mm; duration 20 ns). Each test pulse produced visible sparks and focal projectile ejection of skin with pox-like scar formation. Caution is advised when using the QSRL for the treatment of traumatic tattoos composed of potentially combustible debris.

Engineering education research: Impacts of an international network of female engineers on the persistence of Liberian undergraduate women studying engineering

Science.gov (United States)

Rimer, Sara; Reddivari, Sahithya; Cotel, Aline

2015-11-01

As international efforts to educate and empower women continue to rise, engineering educators are in a unique position to be a part of these efforts by encouraging and supporting women across the world at the university level through STEM education and outreach. For the past two years, the University of Michigan has been a part of a grassroots effort to encourage and support the persistence of engineering female students at University of Liberia. This effort has led to the implementation of a leadership camp this past August for Liberian engineering undergraduate women, meant to: (i) to empower engineering students with the skills, support, and inspiration necessary to become successful and well-rounded engineering professionals in a global engineering market; and (ii) to strengthen the community of Liberian female engineers by building cross-cultural partnerships among students resulting in a international network of women engineers. This session will present qualitative research findings on the impact of this grassroots effort on Liberian female students? persistence in engineering, and the future directions of this work.

Debris Disks: Probing Planet Formation

OpenAIRE

Wyatt, Mark C.

2018-01-01

Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km i...

The impact of cellular debris on Pseudomonas aeruginosa adherence to silicone hydrogel contact lenses and contact lens storage cases.

Science.gov (United States)

Burnham, Geoffrey W; Cavanagh, H Dwight; Robertson, Danielle M

2012-01-01

To evaluate neutrophil-enhanced Pseudomonas aeruginosa (PA) biofilm formation on silicone hydrogel contact lenses and to determine the effect of epithelial biodebris on PA adherence in contact lens storage cases. A fully invasive PA corneal isolate stably conjugated to green fluorescent protein was used. Unworn lotrafilcon A contact lenses were incubated at various ratios of PA to polymorphonuclear neutrophil (PMN) for 24 hours at 37°C. Lens-associated PA was evaluated using laser scanning confocal microscopy and nonviable PA were visualized using propidium iodide. Viable bacteria were enumerated by colony-forming unit (CFU) analysis. For acute epithelial cell studies, PA viability was determined after coincubation with freeze-thaw epithelial cell lysates in 96-well polystyrene plates. Levels of residual cellular debris and bacterial viability were further assessed in used contact lens storage cases. Laser scanning confocal microscopy demonstrated that cotreatment with PMA-stimulated neutrophils increased PA adherence over 24 hours to lens surfaces with a striking alteration of PA architecture. Propidium iodide staining showed that the adherent bacteria consisted of a mixture of viable and nonviable PA; a PMN-associated increase in viable PA was confirmed by CFU (PA:PMN 0.1:1, P = 0.025; PA:PMN 1:1, P = 0.005). Acute epithelial cell debris studies revealed a significant increase in viable PA in 96-well plates in the presence of epithelial freeze-thaw lysates (PA:debris 1:1, P = 0.002; PA:debris 100:1, P = 0.002). Crystal violet staining of used lens storage cases revealed residual cellular debris at all time points, which was independent of microbial contamination; all lens cases used for periods of 9 months or more were uniformly associated with high levels of viable microorganisms. These results demonstrate that prolonged corneal inflammation with the presence of PMNs when confronted with simultaneous PA challenge in extended contact lens wear has the potential

A Ballistic Limit Analysis Program for Shielding Against Micrometeoroids and Orbital Debris

Science.gov (United States)

Ryan, Shannon; Christiansen, Erie

2010-01-01

A software program has been developed that enables the user to quickly and simply perform ballistic limit calculations for common spacecraft structures that are subject to hypervelocity impact of micrometeoroid and orbital debris (MMOD) projectiles. This analysis program consists of two core modules: design, and; performance. The design module enables a user to calculate preliminary dimensions of a shield configuration (e.g., thicknesses/areal densities, spacing, etc.) for a ?design? particle (diameter, density, impact velocity, incidence). The performance module enables a more detailed shielding analysis, providing the performance of a user-defined shielding configuration over the range of relevant in-orbit impact conditions.

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

Science.gov (United States)

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.

Updated Decision Support Tool for the Management of Waste and Debris from Radiological Incidents

International Nuclear Information System (INIS)

Lemieux, P.; Thorneloe, S.; Hayes, C.; Rodgers, M.; Christman, R.

2009-01-01

Unique challenges exist for the handling, transport, and disposal of debris resulting from homeland security incidents, disasters or other national emergencies. Access to guidance for facilitating decision making in the safe and timely disposal of debris is critical to helping restore a community or region and prevent further contamination or spread of disease. For a radiological dispersal device (RDD) or other radiological incident, proper characterization of the quantity, properties, and level of contamination of debris and decontamination residue can have a significant impact on cleanup costs and timelines. A suite of decision support tools (DSTs) is being developed by the U.S. EPA's Office of Research and Development to assist individuals responsible for making decisions associated with handling, transport, treatment, and disposal of such debris. The DSTs are location-specific to help identify specific facilities and contacts for making final disposal decisions. The DSTs provide quick reference to technical information, regulations, and other information to provide decision makers with assistance in guiding disposal decisions that are important for the protection of public health, first responders, and the environment. This tool is being developed in partnership with other U.S. government agencies, EPA program offices, industry, and state and local emergency response programs. (authors)

Debris filtering efficiency and its effect on long term cooling capability

International Nuclear Information System (INIS)

Jung, Min-Su; Kim, Kyu-Tae

2013-01-01

Highlights: • Debris filtering efficiencies for two debris filter designs used in PWRs are provided. • Various debris used in the tests are selected to simulate actual debris found in PWRs. • Debris filter efficiency is explained by flow-hole size and grid strap height. • The effect of debris filters on flow blockage during LTC after a LOCA is described. -- Abstract: A cutting-edge debris-filter designs, Protective Grid (P-grid) and Guardian Grid (G-grid) attached to the upper part of bottom nozzle, have been employed for the PWRs in Korea since 2000s to protect the fuel from debris-induced fuel failures. The debris-filter efficiency of the P-grid and G-grid designs is improved by relatively smaller flow areas formed by the grid straps and dimples. The debris-filter efficiency of the P-grid design is further improved by the relatively smaller flow-hole bottom nozzle. The debris-filter flow tests employing eighteen debris types showed that the debris-filter efficiencies of the P-grid and G-grid designs are 91 and 96%, respectively, while that of the SYS80 fuel design having only the standard flow-hole bottom nozzle is 26%. The slightly better debris-filter efficiency of the G-grid design against the P-grid design may be explained by relatively smaller flow areas at the G-grid dimple region as well as by the relatively longer solid end plug and the higher G-grid strap. The P-grid design may capture circular shapes of debris larger than 3.44 mm in diameter at the flow holes formed by the P-grid dimples, whereas the G-grid design may capture circular shapes of debris larger than 2.54 mm in diameter at the flow holes formed by the G-grid dimples. The aforementioned difference in the debris-filter efficiency between the P-grid and G-grid designs may be predicted by the solid modeling technique generating three-dimensional flow paths. Using the minimum flow-hole areas generated by the P-grid and G-grid designs, on the other hand, the effect of debris injected from

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

Science.gov (United States)

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

2015-07-15

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

Numerical simulation for debris bed behavior in sodium cooled fast reactor

International Nuclear Information System (INIS)

Tagami, Hirotaka; Tobita, Yoshiharu

2014-01-01

For safety analysis of SFR, it is necessary to evaluate behavior along with coolability of debris bed in lower plenum which is formed in severe accident. In order to analyze debris behavior, model for dense sediment particles behavior was proposed and installed in SFR safety analysis code SIMMER. SIMMER code could adequately reproduce experimental results simulating the self-leveling phenomena with appropriate model parameters for bed stiffness. In reactor condition, the self-leveling experiment for prototypical debris bed has not been performed. Additionally, the prototypical debris bed consists of non-spherical particles and it is difficult to quantify model parameters. This situation brings sensitivity analysis to investigate effect of model parameters on the self-leveling phenomena of prototypical debris bed in present paper. As initial condition for sensitivity analysis, simple mound-like debris bed in sodium-filled lower plenum in reactor vessel is considered. The bed consists of the mixture of fuel debris of 3,300 kg and steel debris of 1,570 kg. Decay heat is given to this fuel debris. The model parameter is chosen as sensitivity parameter. Sensitivity analysis shows that the model parameters can effect on intensity of self-leveling phenomena and eventual flatness of bed. In all analyses, however, coolant and sodium vapor break the debris bed at mainly center part of bed and the debris is relocated to outside of bed. Through this process, the initial debris bed is almost planarized before re-melting of debris. This result shows that the model parameters affect the self-leveling phenomena, but its effect in the safety analysis of SFRs is limited. (author)

An eddy covariance system to characterize the atmospheric surface layer and turbulent latent heat fluxes over a debris-covered Himalayan glacier.

Science.gov (United States)

Litt, Maxime; Steiner, Jakob F.; Stigter, Emmy E.; Immerzeel, Walter; Shea, Joseph Michael

2017-04-01

Over debris-covered glaciers, water content variations in the debris layer can drive significant changes in its thermal conductivity and significantly impact melt rates. Since sublimation and evaporation are favoured in high-altitude conditions, e.g., low atmospheric pressure and high wind speeds, they are expected to strongly influence the water balance of the debris-layer. Dedicated latent heat fluxes measurements at the debris surface are essential to characterize the debris heat conductivity in order to assess underlying ice melt. Furthermore, the contribution of the turbulent fluxes in the surface energy balance over debris covered glacier remains uncertain since they are generally evaluated through similarity methods which might not be valid in complex terrain. We present the first results of a 15-day eddy-covariance experiment installed at the end of the monsoon (September-October) on a 3-m tower above the debris-covered Lirung glacier in Nepal. The tower also included measurements of the 4 radiation components. The eddy covariance measurements allowed for the characterization of the turbulence in the atmospheric surface layer, as well as the direct measurements of evaporation, sublimation and turbulent sensible heat fluxes. The experiment helps us to evaluate the contribution of turbulent fluxes to the surface energy balance over this debris-covered glacier, through a precise characterization of the overlying turbulent atmospheric surface layer. It also helps to study the role of the debris-layer water content changes through evaporation and sublimation and its feedback on heat conduction in this layer. The large observed turbulent fluxes play a significant role in the energy balance at the debris surface and significantly influence debris moisture, conductivity and subsequently underlying ice melt.

Historical summary of the Three Mile Island Unit 2 core debris transportation campaign

Energy Technology Data Exchange (ETDEWEB)

Schmitt, R.C.; Tyacke, M.J. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Quinn, G.J. [Wastren, Inc., Germantown, MD (United States)

1993-03-01

Transport of the damaged core materials from the Unit 2 reactor of the Three Mile Island Nuclear Power Station (TMI-2) to the Idaho National Engineering Laboratory (INEL) for examination and storage presented many technical and institutional challenges, including assessing the ability to transport the damaged core; removing and packaging core debris in ways suitable for transport; developing a transport package that could both meet Federal regulations and interface with the facilities at TMI-2 and the INEL; and developing a transport plan, support logistics, and public communications channels suited to the task. This report is a historical summary of how the US Department of Energy addressed those challenges and transported, received, and stored the TMI-2 core debris at the INEL. Subjects discussed include preparations for transport, loading at TMI-2, institutional issues, transport operations, receipt and storage at the INEL, governmental inquiries/investigations, and lessons learned. Because of public attention focused on the TMI-2 Core Debris Transport Program, the exchange of information between the program and public was extensive. This exchange is a focus for parts of this report to explain why various operations were conducted as they were and why certain technical approaches were employed. And, because of that exchange, the program may have contributed to a better public understanding of such actions and may contribute to planning and execution of similar future actions.

Historical summary of the Three Mile Island Unit 2 core debris transportation campaign

International Nuclear Information System (INIS)

Schmitt, R.C.; Tyacke, M.J.; Quinn, G.J.

1993-03-01

Transport of the damaged core materials from the Unit 2 reactor of the Three Mile Island Nuclear Power Station (TMI-2) to the Idaho National Engineering Laboratory (INEL) for examination and storage presented many technical and institutional challenges, including assessing the ability to transport the damaged core; removing and packaging core debris in ways suitable for transport; developing a transport package that could both meet Federal regulations and interface with the facilities at TMI-2 and the INEL; and developing a transport plan, support logistics, and public communications channels suited to the task. This report is a historical summary of how the US Department of Energy addressed those challenges and transported, received, and stored the TMI-2 core debris at the INEL. Subjects discussed include preparations for transport, loading at TMI-2, institutional issues, transport operations, receipt and storage at the INEL, governmental inquiries/investigations, and lessons learned. Because of public attention focused on the TMI-2 Core Debris Transport Program, the exchange of information between the program and public was extensive. This exchange is a focus for parts of this report to explain why various operations were conducted as they were and why certain technical approaches were employed. And, because of that exchange, the program may have contributed to a better public understanding of such actions and may contribute to planning and execution of similar future actions

EDDA: integrated simulation of debris flow erosion, deposition and property changes

Science.gov (United States)

Chen, H. X.; Zhang, L. M.

2014-11-01

Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA, is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of debris flow mixture is determined at limit equilibrium using the Mohr-Coulomb equation, which is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, a variable time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional dam-break water flow and a one-dimensional debris flow with constant properties. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

Phase shifting-based debris effect detection in USV-assisted AFM nanomachining

Energy Technology Data Exchange (ETDEWEB)

Shi, Jialin [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100049 (China); Liu, Lianqing, E-mail: lianqingliu@sia.cn [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); Yu, Peng; Cong, Yang [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences (CAS), Shenyang, Liaoning 110016 (China); Li, Guangyong [Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA 15213 (United States)

2017-08-15

Highlights: • The mechanism of the debris effect on machining depth in force control mode operation is analyzed. • The relationship between phase shifting and pile-up of debris is investigated. • The phase shifting-based method is hardly affected by the pile-up of debris. • Debris effect detection by phase shifting-based method is achived. - Abstract: Atomic force microscopy (AFM) mechanical-based lithography attracts much attention in nanomanufacturing due to its advantages of low cost, high precision and high resolution. However, debris effects during mechanical lithography often lead to an unstable machining process and inaccurate results, which limits further applications of AFM-based lithography. There is a lack of a real-time debris detection approach, which is the prerequisite to eventually eliminating the influence of the debris, and of a method that can solve the above problems well. The ultrasonic vibration (USV)-assisted AFM has the ability to sense the machining depth in real time by detecting the phase shifting of cantilever. However, whether the pile-up of debris affect the phase response of cantilever is still lack of investigation. Therefore, we analyzed the mechanism of the debris effect on force control mode and investigated the relationship between phase shifting and pile-up of debris. Theoretical analysis and experimental results reveal that the pile-up of debris have negligible effect on phase shifting of cantilever. Therefore, the phase shifting-based method can detect the debris effect on machining depth in force control mode of AFM machining.

Floating Marine Debris in waters of the Mexican Central Pacific.

Science.gov (United States)

Díaz-Torres, Evelyn R; Ortega-Ortiz, Christian D; Silva-Iñiguez, Lidia; Nene-Preciado, Alejandro; Orozco, Ernesto Torres

2017-02-15

The presence of marine debris has been reported recently in several oceans basins; there is very little information available for Mexican Pacific coasts, however. This research examined the composition, possible sources, distribution, and density of Floating Marine Debris (FMD) during nine research surveys conducted during 2010-2012 in the Mexican Central Pacific (MCP). Of 1820 floating objects recorded, 80% were plastic items. Sources of FMD were determined using key objects, which indicated that the most were related to the presence of the industrial harbor and of a growing fishing industry in the study area. Densities were relatively high, ranging from 40 to 2440objects/km 2 ; the highest densities were recorded in autumn. FMD were distributed near coastal regions, mainly in Jalisco, influenced by river outflow and surface currents. Our results seem to follow worldwide trends and highlight the need for further studies on potential ecological impacts within coastal waters of the MCP. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparative evaluation of debris extruded apically by using, Protaper retreatment file, K3 file and H-file with solvent in endodontic retreatment

Directory of Open Access Journals (Sweden)

Chetna Arora

2012-01-01

Full Text Available Aim: The aim of this study was to evaluate the apical extrusion of debris comparing 2 engine driven systems and hand instrumentation technique during root canal retreatment. Materials and Methods: Forty five human permanent mandibular premolars were prepared using the step-back technique, obturated with gutta-percha/zinc oxide eugenol sealer and cold lateral condensation technique. The teeth were divided into three groups: Group A: Protaper retreatment file, Group B: K3, file Group C: H-file with tetrachloroethylene. All the canals were irrigated with 20ml distilled water during instrumentation. Debris extruded along with the irrigating solution during retreatment procedure was carefully collected in preweighed Eppendorf tubes. The tubes were stored in an incubator for 5 days, placed in a desiccator and then re-weighed. Weight of dry debris was calculated by subtracting the weight of the tube before instrumentation and from the weight of the tube after instrumentation. Data was analyzed using Two Way ANOVA and Post Hoc test. Results : There was statistically significant difference in the apical extrusion of debris between hand instrumentation and protaper retreatment file and K3 file. The amount of extruded debris caused by protaper retreatment file and K3 file instrumentation technique was not statistically significant. All the three instrumentation techniques produced apically extruded debris and irrigant. Conclusion: The best way to minimize the extrusion of debris is by adapting crown down technique therefore the use of rotary technique (Protaper retreatment file, K3 file is recommended.

Coolability of oxidized particulate debris bed accumulated in horizontal narrow gaps

International Nuclear Information System (INIS)

Arai, Y.; Sugiyama, K.; Narabayashi, T.

2007-01-01

When LOCA occurs in a nuclear reactor system, the coolability of the core would be kept as reported at a series of presentations in ICONE14. Therefore the probability of the core meltdown is negligible small. However, from the view point of defense in depth, it is necessary to be sure that the coolability of the bottom of reactor pressure vessel (RPV) is maintained even if a part of the core should melt and a substantial amount of debris should be deposited on the lower plenum. We carried out an experimental study in order to observe the coolability of particulate core-metal debris bed with 12 mm thickness accompanied with rapid heat generation because of oxidization, which was reported at ICONE14. The coolability was assured by a small amount of coolant supply because of high capillary force of oxidized fine particulate debris produced. In the present study, we examined the coolability of particulate debris bed deposited in narrower gap of 1 mm or 5 mm that coolant supply is hard. The particulate debris beds were piled up on the stainless steel sheet with 0.1 mm thickness, which was used to measure the bottom temperatures of particulate debris bed by using a thermo-video camera. We set up a heat supply section with heat input of 2.1 kW, which simulates the hard debris bed deposited on the particulate debris bed as reported for the TMI-2 accident. We measured the temperatures of the bottom surface of the heat supply section and the heat fluxes released into debris bed as well as the temperatures at the bottom of debris bed on the stainless steel sheet. It is found that when only the upper surface of particulate debris bed is in the film boiling, capillary force causes coolant supply to the particulate debris bed. Therefore, in the condition of thicker gap with small particulate debris, coolability of debris bed is improved. We find out that smaller particulate debris is moved by vapor movement. As a result, the area that high capillary force is caused because of

Odours from marine plastic debris induce food search behaviours in a forage fish.

Science.gov (United States)

Savoca, Matthew S; Tyson, Chris W; McGill, Michael; Slager, Christina J

2017-08-16

Plastic pollution is an anthropogenic stressor in marine ecosystems globally. Many species of marine fish (more than 50) ingest plastic debris. Ingested plastic has a variety of lethal and sublethal impacts and can be a route for bioaccumulation of toxic compounds throughout the food web. Despite its pervasiveness and severity, our mechanistic understanding of this maladaptive foraging behaviour is incomplete. Recent evidence suggests that the chemical signature of plastic debris may explain why certain species are predisposed to mistaking plastic for food. Anchovy ( Engraulis sp.) are abundant forage fish in coastal upwelling systems and a critical prey resource for top predators. Anchovy ingest plastic in natural conditions, though the mechanism they use to misidentify plastic as prey is unknown. Here, we presented wild-caught schools of northern anchovy ( Engraulis mordax ) with odour solutions made of plastic debris and clean plastic to compare school-wide aggregation and rheotactic responses relative to food and food odour presentations. Anchovy schools responded to plastic debris odour with increased aggregation and reduced rheotaxis. These results were similar to the effects food and food odour presentations had on schools. Conversely, these behavioural responses were absent in clean plastic and control treatments. To our knowledge, this is the first experimental evidence that adult anchovy use odours to forage. We conclude that the chemical signature plastic debris acquires in the photic zone can induce foraging behaviours in anchovy schools. These findings provide further support for a chemosensory mechanism underlying plastic consumption by marine wildlife. Given the trophic position of forage fish, these findings have considerable implications for aquatic food webs and possibly human health. © 2017 The Author(s).

Development of debris resistant bottom end piece

International Nuclear Information System (INIS)

Lee, Jae Kyung; Sohn, Dong Seong; Yim, Jeong Sik; Hwang, Dae Hyun; Song, Kee Nam; Oh, Dong Seok; Rhu, Ho Sik; Lee, Chang Woo; Kim, Seong Soo; Oh, Jong Myung

1993-12-01

Debris-related fuel failures have been identified as one of the major causes of fuel failures. In order to reduce the possibility of debris-related fuel failures, it is necessary to develop Debris-Resistant Bottom End Piece. For this development, mechanical strength test and pressure drop test were performed, and the test results were analyzed. And the laser cutting, laser welding and electron beam welding technology, which were the core manufacturing technology of DRBEP, were developed. Final design were performed, and the final drawing and specifications were prepared. The prototype of DRBEP was manufactured according to the developed munufacturing procedure. (Author)

Spatial variability and potential impacts of climate change on flood and debris flow hazard zone mapping and implications for risk management

Directory of Open Access Journals (Sweden)

H. Staffler

2008-06-01

Full Text Available The main goals of this study were to identify the alpine torrent catchments that are sensitive to climatic changes and to assess the robustness of the methods for the elaboration of flood and debris flow hazard zone maps to specific effects of climate changes. In this study, a procedure for the identification and localization of torrent catchments in which the climate scenarios will modify the hazard situation was developed. In two case studies, the impacts of a potential increase of precipitation intensities to the delimited hazard zones were studied.

The identification and localization of the torrent and river catchments, where unfavourable changes in the hazard situation occur, could eliminate speculative and unnecessary measures against the impacts of climate changes like a general enlargement of hazard zones or a general over dimensioning of protection structures for the whole territory. The results showed a high spatial variability of the sensitivity of catchments to climate changes. In sensitive catchments, the sediment management in alpine torrents will meet future challenges due to a higher rate for sediment removal from retention basins. The case studies showed a remarkable increase of the areas affected by floods and debris flow when considering possible future precipitation intensities in hazard mapping. But, the calculated increase in extent of future hazard zones lay within the uncertainty of the methods used today for the delimitation of the hazard zones. Thus, the consideration of the uncertainties laying in the methods for the elaboration of hazard zone maps in the torrent and river catchments sensitive to climate changes would provide a useful instrument for the consideration of potential future climate conditions. The study demonstrated that weak points in protection structures in future will become more important in risk management activities.

Dynamics of Flexible MLI-type Debris for Accurate Orbit Prediction

Science.gov (United States)

2014-09-01

debris for accurate propagation under perturbations”, in Proceedings of 65th International Astronautical Congress (IAC 2014), Toronto, Canada , 2014...Surveillance Network ( SSN ) was able to detect more than 900 pieces of debris that were at risk to damage operational spacecraft. In February 10, 2009...created two large debris clouds and the SSN reported that 382 pieces of debris from Iridium 33 and 893 pieces from Cosmos 2251 were created, and

Energy release from a stream of infalling prominence debris on 2011 September 7-8

Science.gov (United States)

Inglis, A. R.; Gilbert, H. R.; Ofman, L.

2017-12-01

In recent years high-resolution and high-cadence EUV imaging has revealed a new phenomenon, impacting prominence debris, where prominence material from failed or partial eruptions can impact the lower atmosphere and release energy. We present a clear example of this phenomenon occurring on 2011 September 7-8. The initial eruption of prominence material was associated with an X1.8-class flare from AR11283, occurring at 22:30 UT on 2011 September 7, resulting in a semi-continuous stream of this material returning to the solar surface between 00:20 - 00:40 UT on 2011 September 8. A substantial area remote from the original active region experienced brightening in multiple EUV channels observed by SDO/AIA. Using the differential emission measure, we estimated the energetic properties of this event. We found that the radiated energy of the impacted plasma was of order 10^27 ergs, while the upper limit on the thermal energy peaked at 10^28 ergs. Based on these estimates we were able to determine the mass content of the debris to be in the range 2x10^14 energy release takes place during these events, and that such impacts may be used as a novel diagnostic tool for investigating prominence material properties.

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

International Nuclear Information System (INIS)

Rhatigan, J.L.

1992-01-01

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

A mineralogical and granulometric study of Cayambe volcano debris avalanche deposit

Science.gov (United States)

Detienne, M.; Delmelle, P.; Guevara, A.; Samaniego, P.; Bustillos, J.; Sonnet, P.; Opfergelt, S.

2013-12-01

Volcano flank/sector collapse represents one of the most catastrophic volcanic hazards. Various volcanic and non-volcanic processes are known to decrease the stability of a volcanic cone, eventually precipitating its gravitational failure. Among them, hydrothermal alteration of volcanic rocks leading to clay mineral formation is recognized as having a large negative impact on rock strength properties. Furthermore, the presence of hydrothermal clays in the collapsing mass influences the behavior of the associated volcanic debris avalanche. In particular, clay-containing debris avalanches seem to travel farther and spread more widely than avalanches of similar volume but which do not incorporate hydrothermally-altered materials. However, the relationship between hydrothermal alteration, flank collapse and debris avalanche behavior is not well understood. The objective of this study is to better determine the volume and composition of hydrothermal clay minerals in the poorly characterized debris avalanche deposit (DAD) of Cayambe composite volcano, located in a densely populated area ~70 km northeast of Quito, Ecuador. Cayambe DAD originated from a sector collapse, which occurred less than 200 ka ago. The DAD is 10-20 m thick and has an estimated total volume of ~0.85 Km3. The H/L ratio (where H is the vertical drop and L is the travel distance of the avalanche) for Cayambe DAD is ~0.095, suggesting a high mobility. In the medial-distal zone, at 9-20 km from its source, the DAD consists of an unstratified and unsorted matrix supporting millimetric to metric clasts. It has a matrix facies (i.e. rich in particles DAD behaved as a cohesive debris flow. Analysis of 13 matrix samples reveals a large variability in particle size distribution. This may reflect poor mixing of the collapsed material during transport. The clay fraction content in the matrix ranges from 15 to 30 wt.%, and does not show a relationship with the sample position in the DAD. Mineralogical

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

Czech Academy of Sciences Publication Activity Database

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

2011-01-01

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

Protecting Spacecraft Fragments from Exposure to Small Debris

OpenAIRE

V. V. Zelentsov

2015-01-01

Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable ...

Anthropogenic effect on avalanche and debris flow activity

OpenAIRE

S. A. Sokratov; Yu. G. Seliverstov; A. L. Shnyparkov; K. P. Koltermann

2013-01-01

The paper presents examples of the change in snow avalanches and debris flows activity due to the anthropogenic pressure on vegetation and relief. The changes in dynamical characteristics of selected snow avalanches and debris flows due to the anthropogenic activity are quantified. The conclusion is made that the anthropogenic effects on the snow avalanches and debris flows activity are more pronounced than the possible effects of the climate change. The necessity is expressed on the unavoida...

SCDAP/RELAP5 modeling of fluid heat transfer and flow losses through porous debris in a light water reactor

International Nuclear Information System (INIS)

Harvego, E. A.; Siefken, L. J.

2000-01-01

The SCDAP/RELAP5 code is being developed at the Idaho National Engineering and Environmental Laboratory under the primary sponsorship of the U.S. Nuclear Regulatory Commission (NRC) to provide best-estimate transient simulations of light water reactor coolant systems during severe accidents. This paper describes the modeling approach used in the SCDAP/RELAP5 code to calculate fluid heat transfer and flow losses through porous debris that has accumulated in the vessel lower head and core regions during the latter stages of a severe accident. The implementation of heat transfer and flow loss correlations into the code is discussed, and calculations performed to assess the validity of the modeling approach are described. The different modes of heat transfer in porous debris include: (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, (5) film boiling, and (6) transition from film boiling to convection to vapor. The correlations for flow losses in porous debris include frictional and form losses. The correlations for flow losses were integrated into the momentum equations in the RELAP5 part of the code. Since RELAP5 is a very general non-homogeneous non-equilibrium thermal-hydraulics code, the resulting modeling methodology is applicable to a wide range of debris thermal-hydraulic conditions. Assessment of the SCDAP/RELAP5 debris bed thermal-hydraulic models included comparisons with experimental measurements and other models available in the open literature. The assessment calculations, described in the paper, showed that SCDAP/RELAP5 is capable of calculating the heat transfer and flow losses occurring in porous debris regions that may develop in a light water reactor during a severe accident

New solutions for the space debris problem

CERN Document Server

Pelton, Joseph N

2015-01-01

Addressing a pressing issue in space policy, Pelton explores the new forms of technology that are being developed to actively remove the defunct space objects from orbit and analyzes their implications in the existing regime of international space law and public international law. This authoritative review covers the due diligence guidelines that nations are using to minimize the generation of new debris, mandates to de-orbit satellites at end of life, and innovative endeavours to remove non-functional satellites, upper stage rockets and other large debris from orbit under new institutional, financial and regulatory guidelines.  Commercial space services currently exceed 100 billion USD business per annum, but the alarming proliferation in the population of orbital debris in low, medium and geosynchronous satellite orbits poses a serious threat to all kinds of space assets and applications. There is a graver concern that the existing space debris will begin to collide in a cascading manner, generating furth...

Laser space debris removal: now, not later

Science.gov (United States)

Phipps, Claude R.

2015-02-01

Small (1-10cm) debris in low Earth orbit (LEO) are extremely dangerous, because they spread the breakup cascade depicted in the movie "Gravity." Laser-Debris-Removal (LDR) is the only solution that can address both large and small debris. In this paper, we briefly review ground-based LDR, and discuss how a polar location can dramatically increase its effectiveness for the important class of sun-synchronous orbit (SSO) objects. No other solutions address the whole problem of large ( 1000cm, 1 ton) as well as small debris. Physical removal of small debris (by nets, tethers and so on) is impractical because of the energy cost of matching orbits. We also discuss a new proposal which uses a space-based station in low Earth orbit (LEO), and rapid, head-on interaction in 10- 40s rather than 4 minutes, with high-power bursts of 100ps, 355nm pulses from a 1.5m diameter aperture. The orbiting station employs "heat-capacity" laser mode with low duty cycle to create an adaptable, robust, dualmode system which can lower or raise large derelict objects into less dangerous orbits, as well as clear out the small debris in a 400-km thick LEO band. Time-average laser optical power is less than 15kW. The combination of short pulses and UV wavelength gives lower required energy density (fluence) on target as well as higher momentum coupling coefficient. This combination leads to much smaller mirrors and lower average power than the ground-based systems we have considered previously. Our system also permits strong defense of specific assets. Analysis gives an estimated cost of about 1k each to re-enter most small debris in a few months, and about 280k each to raise or lower 1-ton objects by 40km. We believe it can do this for 2,000 such large objects in about four years. Laser ablation is one of the few interactions in nature that propel a distant object without any significant reaction on the source.

Nanometer size wear debris generated from ultra high molecular weight polyethylene in vivo

Czech Academy of Sciences Publication Activity Database

Lapčíková, Monika; Šlouf, Miroslav; Dybal, Jiří; Zolotarevova, E.; Entlicher, G.; Pokorný, D.; Gallo, J.; Sosna, A.

2009-01-01

Roč. 266, 1-2 (2009), s. 349-355 ISSN 0043-1648 R&D Projects: GA MŠk 2B06096 Institutional research plan: CEZ:AV0Z40500505 Keywords : ultra high molecular weight polyethylene * nanometer size wear debris * morphology of wear particles Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.771, year: 2009

Apically-extruded debris using the ProTaper system.

Science.gov (United States)

Azar, Nasim Gheshlaghi; Ebrahimi, Gholamreza

2005-04-01

The purpose of this in vitro study was to determine the quantity of debris and irrigant extruded apically using the ProTaper system compared to ProFiles and K-Flexofiles. Thirty-six mesio-buccal root canals of human mandibular molars were selected and divided into three groups of twelve canals. Two groups were instrumented with ProFiles and ProTapers according to the manufacturer's instructions. The other group was instrumented with K-Flexofiles using the step-back technique. A standard amount of irrigant was used for each canal. Apically-extruded debris and irrigant was collected in pre-weighed vials. The mean weight of extruded debris and irrigant for each group was statistically analysed using Student's t-test and one-way ANOVA. All instrumentation techniques produced extruded debris and irrigant. Although the mean amount of extrusion with the step-back technique was higher than the two rotary systems, there was no significant difference between the three groups (p > 0.05). NiTi rotary systems were associated with less apical extrusion, but were not significantly better than hand file instrumentation. All techniques extruded debris.

Optical Photometric Observations of GEO Debris

Science.gov (United States)

Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Edwin S.; Abercromby, Kira J.; Kelecy, Thomas M.; Horstman, Matt

2010-01-01

We report on a continuing program of optical photometric measurements of faint orbital debris at geosynchronous Earth orbit (GEO). These observations can be compared with laboratory studies of actual spacecraft materials in an effort to determine what the faint debris at GEO may be. We have optical observations from Cerro Tololo Inter-American Observatory (CTIO) in Chile of two samples of debris: 1. GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Curtis-Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 t11 magnitude that are discovered in the MODEST survey. 2. A smaller sample of high area to mass ratio (AMR) objects discovered independently, and acquired using predictions from orbits derived from independent tracking data collected days prior to the observations. Our optical observations in standard astronomical BVRI filters are done with either telescope, and with the telescope tracking the debris object at the object's angular rate. Observations in different filters are obtained sequentially. We have obtained 71 calibrated sequences of R-B-V-I-R magnitudes. A total of 66 of these sequences have 3 or more good measurements in all filters (not contaminated by star streaks or in Earth's shadow). Most of these sequences show brightness variations, but a small subset has observed brightness variations consistent with that expected from observational errors alone. The majority of these stable objects are redder than a solar color in both B-R and R-I. There is no dependence on color with brightness. 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

ROGER a potential orbital space debris removal system

Science.gov (United States)

Starke, Juergen; Bischof, Bernd; Foth, W.-O.; -J., J.; Günther

The previous activities in the field of On Orbit Servicing studied in the 1990's included in partic-ular the capability of vehicles in GEO to capture and support satellites (mainly communication satellites) to enable repair and continuation of operations, and finally the controlled transfer the target into a permanent graveyard orbit. The specific capture tools for these applications were mostly based on robotic systems to capture and fix the target under specific dynamic constraints (e.g. slowly tumbling target) without damage, and to allow the stabilization, re-orientation and potential repair of the target and subsequent release or transport to the final disposal orbit. Due to the drastically increasing number of debris particularly in the Low Earth Orbits (SSO) the active debris removal is now necessary to counteract to the predicted debris production cascade (Kessler Syndrome), which means the pollution of the total sphere in low earth orbit and not only the SSO area. In most of the debris congresses it was recommended to start removal with the still integrated systems as soon as possible. In the case of large debris objects, the soft capture system can be replaced by a simpler and robust system able to operate from a safe distance to the target and flexible enough to capture and hold different types of targets such as deactivated and/or defective satellites, upper stages and big fragments. These nominally non -cooperative targets might be partially destroyed by the capture process, but the production of additional debris shall be avoided. A major argument for the commercial applications is a multi-target mission potential, which is possible at GEO because the transfer propellant requirement to the disposal orbit and the return to the orbit of the next potential target is relative low (orbits with similar inclination and altitude). The proposed ROGER system is designed as a spacecraft with rendezvous capabilities including inspection in the vicinity of the

Investigation of debris bed formation, spreading and coolability

Energy Technology Data Exchange (ETDEWEB)

Kudinov, P.; Konovalenko, A.; Grishchenko, D.; Yakush, S.; Basso, S.; Lubchenko, N.; Karbojian, A. [Royal Institute of Technology, KTH. Div. of Nuclear Power Safety, Stockholm (Sweden)

2013-08-15

The work is motivated by the severe accident management strategy adopted in Nordic type BWRs. It is assumed that core melt ejected from the vessel will fragment, quench and form a coolable debris bed in a deep water pool below the vessel. In this work we consider phenomena relevant to the debris bed formation and coolability. Several DEFOR-A (Debris Bed Formation - Agglomeration) tests have been carried out with new corium melt material and a melt releasing nozzle mockup. The influence of the melt material, melt superheat, jet free fall height on the (i) faction of agglomerated debris, (ii) particle size distribution, (iii) ablation/plugging of the nozzle mockup has been addressed. Results of the DECOSIM (Debris Coolability Simulator) code validation against available COOLOCE data are presented in the report. The dependence of DHF on system pressure from COOLOCE experiments can be reproduced quite accurately if either the effective particle diameter or debris bed porosity is increased. For a cylindrical debris bed, good agreement is achieved in DECOSIM simulations for the particle diameter 0.89 mm and porosity 0.4. The results obtained are consistent with MEWA simulation where larger particle diameters and porosities were found to be necessary to reproduce the experimental data on DHF. It is instructive to note that results of DHF prediction are in better agreement with POMECO-HT data obtained for the same particles. It is concluded that further clarification of the discrepancies between different experiments and model predictions. In total 13 exploratory tests were carried out in PDS (particulate debris spreading) facility to clarify potential influence of the COOLOCE (VTT) facility heaters and TCs on particle self-leveling process. Results of the preliminary analysis suggest that there is no significant influence of the pins on self-leveling, at least for the air superficial velocities ranging from 0.17 up to 0.52 m/s. Further confirmatory tests might be needed

Investigation of debris bed formation, spreading and coolability

International Nuclear Information System (INIS)

Kudinov, P.; Konovalenko, A.; Grishchenko, D.; Yakush, S.; Basso, S.; Lubchenko, N.; Karbojian, A.

2013-08-01

The work is motivated by the severe accident management strategy adopted in Nordic type BWRs. It is assumed that core melt ejected from the vessel will fragment, quench and form a coolable debris bed in a deep water pool below the vessel. In this work we consider phenomena relevant to the debris bed formation and coolability. Several DEFOR-A (Debris Bed Formation - Agglomeration) tests have been carried out with new corium melt material and a melt releasing nozzle mockup. The influence of the melt material, melt superheat, jet free fall height on the (i) faction of agglomerated debris, (ii) particle size distribution, (iii) ablation/plugging of the nozzle mockup has been addressed. Results of the DECOSIM (Debris Coolability Simulator) code validation against available COOLOCE data are presented in the report. The dependence of DHF on system pressure from COOLOCE experiments can be reproduced quite accurately if either the effective particle diameter or debris bed porosity is increased. For a cylindrical debris bed, good agreement is achieved in DECOSIM simulations for the particle diameter 0.89 mm and porosity 0.4. The results obtained are consistent with MEWA simulation where larger particle diameters and porosities were found to be necessary to reproduce the experimental data on DHF. It is instructive to note that results of DHF prediction are in better agreement with POMECO-HT data obtained for the same particles. It is concluded that further clarification of the discrepancies between different experiments and model predictions. In total 13 exploratory tests were carried out in PDS (particulate debris spreading) facility to clarify potential influence of the COOLOCE (VTT) facility heaters and TCs on particle self-leveling process. Results of the preliminary analysis suggest that there is no significant influence of the pins on self-leveling, at least for the air superficial velocities ranging from 0.17 up to 0.52 m/s. Further confirmatory tests might be needed

Global Analysis of Anthropogenic Debris Ingestion by Sea Turtles

Science.gov (United States)

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

2014-01-01

Ingestion of marine debris can have lethal and sublethal effects on sea turtles and other wildlife. Although researchers have reported on ingestion of anthropogenic debris by marine turtles and implied incidences of debris ingestion have increased over time, there has not been a global synthesis of the phenomenon since 1985. Thus, we analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011. Specifically, we investigated whether ingestion prevalence has changed over time, what types of debris are most commonly ingested, the geographic distribution of debris ingestion by marine turtles relative to global debris distribution, and which species and life-history stages are most likely to ingest debris. The probability of green (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) ingesting debris increased significantly over time, and plastic was the most commonly ingested debris. Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities. Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores. Our results indicate oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris. To reduce this risk, anthropogenic debris must be managed at a global level. Análisis Global de la Ingesta de Residuos Antropogénicos por Tortugas Marinas La ingesta de residuos marinos puede tener efectos letales y subletales sobre las tortugas marinas y otros animales. Aunque hay investigadores que han reportado la ingesta de residuos antropogénicos por tortugas marinas y la incidencia de la ingesta de residuos ha incrementado con el tiempo, no ha habido una síntesis global del fenómeno desde 1985. Por esto analizamos 37 estudios publicados, desde

Characterizing Longitude-Dependent Orbital Debris Congestion in the Geosynchronous Orbit Regime

Science.gov (United States)

Anderson, Paul V.

The geosynchronous orbit (GEO) is a unique commodity of the satellite industry that is becoming increasingly contaminated with orbital debris, but is heavily populated with high-value assets from the civil, commercial, and defense sectors. The GEO arena is home to hundreds of communications, data transmission, and intelligence satellites collectively insured for an estimated 18.3 billion USD. As the lack of natural cleansing mechanisms at the GEO altitude renders the lifetimes of GEO debris essentially infinite, conjunction and risk assessment must be performed to safeguard operational assets from debris collisions. In this thesis, longitude-dependent debris congestion is characterized by predicting the number of near-miss events per day for every longitude slot at GEO, using custom debris propagation tools and a torus intersection metric. Near-miss events with the present-day debris population are assigned risk levels based on GEO-relative position and speed, and this risk information is used to prioritize the population for debris removal target selection. Long-term projections of debris growth under nominal launch traffic, mitigation practices, and fragmentation events are also discussed, and latitudinal synchronization of the GEO debris population is explained via node variations arising from luni-solar gravity. In addition to characterizing localized debris congestion in the GEO ring, this thesis further investigates the conjunction risk to operational satellites or debris removal systems applying low-thrust propulsion to raise orbit altitude at end-of-life to a super-synchronous disposal orbit. Conjunction risks as a function of thrust level, miss distance, longitude, and semi-major axis are evaluated, and a guidance method for evading conjuncting debris with continuous thrust by means of a thrust heading change via single-shooting is developed.

Spiders (Araneae of stony debris in North Bohemia

Directory of Open Access Journals (Sweden)

Růžička, Vlastimil

1996-12-01

Full Text Available The arachnofauna was studied at five stony debris sites in northern Bohemia. In Central Europe, the northern and montane species inhabiting cold places live not only on mountain tops and peat bogs but also on the lower edges of boulder debris, where air streaming through the system of inner compartments gives rise to an exceedingly cold microclimate. At such cold sites, spiders can live either on bare stones (Bathyphantes simillimus, Wubanoides uralensis, or in the rich layers of moss and lichen (Diplocentria bidentata. Kratochviliella bicapitata exhibits a diplostenoecious occurence in stony debris and on the tree bark. Latithorax faustus and Theonoe minutissima display diplostenoecious occurence in stony debris and on peat bogs. The occurence of the species Scotina celans in the Czech Republic was documented for the first time.

DFLOWZ: A free program to evaluate the area potentially inundated by a debris flow

Science.gov (United States)

Berti, M.; Simoni, A.

2014-06-01

The transport and deposition mechanisms of debris flows are still poorly understood due to the complexity of the interactions governing the behavior of water-sediment mixtures. Empirical-statistical methods can therefore be used, instead of more sophisticated numerical methods, to predict the depositional behavior of these highly dangerous gravitational movements. We use widely accepted semi-empirical scaling relations and propose an automated procedure (DFLOWZ) to estimate the area potentially inundated by a debris flow event. Beside a digital elevation model (DEM), the procedure has only two input requirements: the debris flow volume and the possible flow-path. The procedure is implemented in Matlab and a Graphical User Interface helps to visualize initial conditions, flow propagation and final results. Different hypothesis about the depositional behavior of an event can be tested together with the possible effect of simple remedial measures. Uncertainties associated to scaling relations can be treated and their impact on results evaluated. Our freeware application aims to facilitate and speed up the process of susceptibility mapping. We discuss limits and advantages of the method in order to inform inexperienced users.

Deposition of steeply infalling debris around white dwarf stars

Science.gov (United States)

Brown, John C.; Veras, Dimitri; Gänsicke, Boris T.

2017-06-01

High-metallicity pollution is common in white dwarf (WD) stars hosting remnant planetary systems. However, they rarely have detectable debris accretion discs, possibly because much of the influx is fast steeply infalling debris in star-grazing orbits, producing a more tenuous signature than a slowly accreting disc. Processes governing such deposition between the Roche radius and photosphere have so far received little attention and we model them here analytically by extending recent work on sun-grazing comets to WD systems. We find that the evolution of cm-to-km size (a0) infallers most strongly depends on two combinations of parameters, which effectively measure sublimation rate and binding strength. We then provide an algorithm to determine the fate of infallers for any WD, and apply the algorithm to four limiting combinations of hot versus cool (young/old) WDs with snowy (weak, volatile) versus rocky (strong, refractory) infallers. We find: (I) Total sublimation above the photosphere befalls all small infallers across the entire WD temperature (TWD) range, the threshold size rising with TWD and 100× larger for rock than snow. (II) All very large objects fragment tidally regardless of TWD: for rock, a0 ≽ 105 cm; for snow, a0 ≽ 103-3 × 104 cm across all WD cooling ages. (III) A considerable range of a0 avoids fragmentation and total sublimation, yielding impacts or grazes with cold WDs. This range rapidly narrows with increasing TWD, especially for snowy bodies. Finally, we briefly discuss how the various forms of deposited debris may finally reach the photosphere surface itself.

Reduced sulfur compounds in gas from construction and demolition debris landfills.

Science.gov (United States)

Lee, Sue; Xu, Qiyong; Booth, Matthew; Townsend, Timothy G; Chadik, Paul; Bitton, Gabriel

2006-01-01

The biological conversion of sulfate from disposed gypsum drywall to hydrogen sulfide (H(2)S) in the anaerobic environment of a landfill results in odor problems and possible health concerns at many disposal facilities. To examine the extent and magnitude of such emissions, landfill gas samples from wells, soil vapor samples from the interface of the waste and cover soil, and ambient air samples, were collected from 10 construction and demolition (C&D) debris landfills in Florida and analyzed for H(2)S and other reduced sulfur compounds (RSC). H(2)S was detected in the well gas and soil vapor at all 10 sites. The concentrations in the ambient air above the surface of the landfill were much lower than those observed in the soil vapor, and no direct correlation was observed between the two sampling locations. Methyl mercaptan and carbonyl sulfide were the most frequently observed other RSC, though they occurred at smaller concentrations than H(2)S. This research confirmed the presence of H(2)S at C&D debris landfills. High concentrations of H(2)S may be a concern for employees working on the landfill site. These results indicate that workers should use proper personal protection at C&D debris landfills when involved in excavation, landfill gas collection, or confined spaces. The results indicate that H(2)S is sufficiently diluted in the atmosphere to not commonly pose acute health impacts for these landfill workers in normal working conditions. H(2)S concentrations were extremely variable with measurements occurring over a very large range (from less than 3 ppbv to 12,000 ppmv in the soil vapor and from less than 3 ppbv to 50 ppmv in ambient air). Possible reasons for the large intra- and inter-site variability observed include waste and soil heterogeneities, impact of weather conditions, and different site management practices.

Classification of debris flow phenomena in the Faroe Islands

DEFF Research Database (Denmark)

Dahl, Mads-Peter Jakob; E. Mortensen, Lis; Jensen, Niels H.

2012-01-01

Landslides and debris flow phenomena in particular constitute a threat to human activities in the Faroe Islands. As a contribution to ongoing landslide risk management research, this paper proposes a classification scheme for debris flow phenomena in the Faroe Islands. The scheme, produced through...... a multidisciplinary study involving geomorphological fieldwork and qualitative collection of indigenous landslide knowledge, presents physical characteristics to classify debris flow phenomena into groups named with Faroese terms. The following landslide definitions are proposed. Brekku-skriðulop (English translation...... with international landslide classification systems, significantly increases the knowledge of debris flow phenomena and promotes a consistent terminology of these within the Faroe Islands....

ASTM standards for fire debris analysis: a review.

Science.gov (United States)

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.

Property measurements and inner state estimation of simulated fuel debris

Energy Technology Data Exchange (ETDEWEB)

Hirooka, S.; Kato, M.; Morimoto, K.; Washiya, T. [Japan Atomic Energy Agency, Ibaraki (Japan)

2014-07-01

Fuel debris properties and inner state such as temperature profile were evaluated by using analysis of simulated fuel debris manufactured from UO{sub 2} and oxidized zircaloy. The center of the fuel debris was expected to be molten state soon after the melt down accident of LWRs because power density was very high. On the other hand, the surface of the fuel debris was cooled in the water. This large temperature gradient may cause inner stress and consequent cracks were expected. (author)

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

Science.gov (United States)

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

2012-01-01

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

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

Directory of Open Access Journals (Sweden)

Qamar Schuyler

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

Sediment delivery in debris-flow torrents: two case studies in the Italian Alps

Science.gov (United States)

Bertoldi, Gabriele; Vincenzo, D'Agostino

2013-04-01

Flood-risk mitigation strategy is moving from fixed, structural and costly mitigation measures to more effective proactive solutions. This change is driven both by Flood Directive 2007/60/EC and limitations of financial resources and it requires a deep knowledge of the involved processes. In mountain catchments debris flow and debris floods are the most important sources of hazard and their impact on the fan areas is heavily conditioned by the sediment dynamics along the 'transport' reaches of the torrents. Last advances show how many cases of erosion and deposition within the transport reach greatly affect the total volume that is delivered to the fan as well the overall dynamics of the debris flow/flood event. Due to logistic and practical constraints this intermediate phase of the process has been scarcely investigated and the complex behavior of the sediment budgeting in torrent-streams is emerging. The objective of this work consists of collecting information on the evolution of the debris-flow sediment budget along Alpine torrents in order to provide novel data about erosive, depositional and recharging processes under different geological conditions. Two high frequency debris-flow catchments have been selected: the Rio Rudan basin in the geological setting of the Dolomites (near Cortina d'Ampezzo, Veneto Region, Italy) and the metamorphic dominated catchment of the Rio Gadria (near Lasa, Trentino Alto Adige, Italy), which has been recently instrumented (EU project Monitor II). Periodical field monitoring has been carried out since summer 2011. 25 cross sections have been observed in the Rio Rudan catchment along a 480 m torrent reach (slope of 36%) where additional sediment entrainment after debris-flow initiation takes place. 20 cross sections have been selected in the upper Rio Gadria basin and more precisely in two reaches close to debris-flow triggerring areas. Other 31 cross sections have been also monitored of the Rio Gadria main channel covering a

Mapping coastal marine debris using aerial imagery and spatial analysis.

Science.gov (United States)

Moy, Kirsten; Neilson, Brian; Chung, Anne; Meadows, Amber; Castrence, Miguel; Ambagis, Stephen; Davidson, Kristine

2017-12-19

This study is the first to systematically quantify, categorize, and map marine macro-debris across the main Hawaiian Islands (MHI), including remote areas (e.g., Niihau, Kahoolawe, and northern Molokai). Aerial surveys were conducted over each island to collect high resolution photos, which were processed into orthorectified imagery and visually analyzed in GIS. The technique provided precise measurements of the quantity, location, type, and size of macro-debris (>0.05m 2 ), identifying 20,658 total debris items. Northeastern (windward) shorelines had the highest density of debris. Plastics, including nets, lines, buoys, floats, and foam, comprised 83% of the total count. In addition, the study located six vessels from the 2011 Tōhoku tsunami. These results created a baseline of the location, distribution, and composition of marine macro-debris across the MHI. Resource managers and communities may target high priority areas, particularly along remote coastlines where macro-debris counts were largely undocumented. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preserving the Near-Earth Space Environment with Green Engineering and Operations

Science.gov (United States)

Johnson, Nicholas L.

2009-01-01

Green engineering and operations are essential to preserving the near-Earth space environment for future generations. The U.S. and the international aerospace community have been proactive in addressing the threat of the increasing orbital debris population and the risks to people and property from reentering debris. NASA has led this activity first by devoting resources to thoroughly understand the technical issues and then by developing effective and acceptable policies and guidelines. NASA also worked closely with the international community to ensure that the US aerospace industry was not placed at an economic disadvantage. In the long term, the removal of large orbital debris will be essential to the sustainability of space operations.

The world state of orbital debris measurements and modeling

Science.gov (United States)

Johnson, Nicholas L.

2004-02-01

For more than 20 years orbital debris research around the world has been striving to obtain a sharper, more comprehensive picture of the near-Earth artificial satellite environment. Whereas significant progress has been achieved through better organized and funded programs and with the assistance of advancing technologies in both space surveillance sensors and computational capabilities, the potential of measurements and modeling of orbital debris has yet to be realized. Greater emphasis on a systems-level approach to the characterization and projection of the orbital debris environment would prove beneficial. On-going space surveillance activities, primarily from terrestrial-based facilities, are narrowing the uncertainties of the orbital debris population for objects greater than 2 mm in LEO and offer a better understanding of the GEO regime down to 10 cm diameter objects. In situ data collected in LEO is limited to a narrow range of altitudes and should be employed with great care. Orbital debris modeling efforts should place high priority on improving model fidelity, on clearly and completely delineating assumptions and simplifications, and on more thorough sensitivity studies. Most importantly, however, greater communications and cooperation between the measurements and modeling communities are essential for the efficient advancement of the field. The advent of the Inter-Agency Space Debris Coordination Committee (IADC) in 1993 has facilitated this exchange of data and modeling techniques. A joint goal of these communities should be the identification of new sources of orbital debris.

Preliminary results from initial in-pile debris bed experiments

International Nuclear Information System (INIS)

Rivard, J.B.

1977-01-01

An accident in a liquid metal fast breeder reactor (LMFBR) in which molten core material is suddenly quenched with subcooled liquid sodium could result in extensive fragmentation and dispersal of fuel as subcritical beds of frozen particulate debris within the reactor vessel. Since this debris will continue to generate power due to decay of retained fission products, containment of the debris is threatened if the generated heat is not removed. Therefore, the initial safety question is the capacity which debris beds may have for transfer of the decay heat to overlying liquid sodium by natural processes--i.e., without the aid of forced circulation of the coolant. Up to the present time, all experiments on debris bed behavior either have used substitute materials (e.g., sand and water) or have employed actual materials, but atypical heating methods. Increased confidence in the applicability of debris bed simulations is afforded if the heat is generated within the fuel component of the appropriate fast reactor materials. The initial series of in-pile tests reported on herein constitutes the first experiments in which the internal heating mode has been produced in particulate oxide fuel immersed in liquid sodium. Fission heating of the fully-enriched UO 2 in the experiment while it is contained within Sandia Laboratories Annular Core Pulse Reactor (ACPR), operating in its steady-state mode, approximates the decay heating of debris. Preliminary results are discussed

Woody debris transport modelling by a coupled DE-SW approach

Science.gov (United States)

Persi, Elisabetta; Petaccia, Gabriella; Sibilla, Stefano

2016-04-01

debris motion. References Comiti, F. et al., 2008. Large wood and flash floods: Evidence from the 2007 event in the Davča basin (Slovenia). WIT Transactions on Engineering Sciences, 60, pp.173-182. Gippel, C.J. et al., 1996. Hydraulic Guidelines for the Re-Introduction and Management of Large Woody Debris in Lowland Rivers. Regulated Rivers: Research & Management, 12, pp.223-236. Available at: http://doi.wiley.com/10.1002/(SICI)1099-1646(199603)12:2/33.3.CO;2-R. Hoang, M.C., Laneville, A. & Légeron, F., 2015. Experimental study on aerodynamic coefficients of yawed cylinders. Journal of Fluids and Structures, 54, pp.597-611. Available at: http://linkinghub.elsevier.com/retrieve/pii/S0889974615000067. Lange, D. & Bezzola, G.R., 2006. Schwemmholz-Probleme und Lösungsansätze. Mitteilungen, 188. Ruiz-Villanueva, V. et al., 2014. Two-dimensional numerical modeling of wood transport. Journal of Hydroinformatics, 16(5), p.1077. Available at: http://www.iwaponline.com/jh/016/jh0161077.htm.

Anthropogenic debris in the nests of kelp gulls in South Africa.

Science.gov (United States)

Witteveen, Minke; Brown, Mark; Ryan, Peter G

2017-01-30

Anthropogenic debris results in detrimental interactions with many marine species. Several seabirds include debris items in their nests, which can lead to entanglement of chicks and adults, resulting in injury or death. Anthropogenic debris was found in 4-67% of kelp gull Larus dominicanus nests in seven colonies in the Western Cape, South Africa. Nests contained two types of litter: items included in the nest structure during construction (mainly ropes and straps), and regurgitated items (mainly bags and food wrappers) that probably accumulate primarily during the chick-rearing period. Debris used in nest construction was more likely to injure gulls, and was found mainly at coastal sites where there was little natural vegetation for construction. Distance to the nearest urban waste landfill significantly affected the occurrence of debris items in nests, especially dietary-derived items. The amount of debris in kelp gull nests highlights the need for improved debris management in South Africa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Debris flows risk analysis and direct loss estimation: the case study of Valtellina di Tirano, Italy

Czech Academy of Sciences Publication Activity Database

Blahůt, Jan; Glade, T.; Sterlacchini, S.

2014-01-01

Roč. 11, č. 2 (2014), s. 288-307 ISSN 1672-6316 Institutional support: RVO:67985891 Keywords : Debris flows * Risk analysis * Economic losses * Central Alps * Italy Subject RIV: DE - Earth Magnetism, Geodesy, Geography OBOR OECD: Physical geography Impact factor: 0.963, year: 2014

Study on the leaching behavior of actinides from nuclear fuel debris

Science.gov (United States)

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.

Transport of sediment through a channel network during a post-fire debris flow

Science.gov (United States)

Nyman, P.; Box, W. A. C.; Langhans, C.; Stout, J. C.; Keesstra, S.; Sheridan, G. J.

2017-12-01

Transport processes linking sediment in steep headwaters with rivers during high magnitude events are rarely examined in detail, particularly in forested settings where major erosion events are rare and opportunities for collecting data are limited. Yet high magnitude events in headwaters are known to drive landscape change. This study examines how a debris flow after wildfire impacts on sediment transport from small headwaters (0.02 km2) through a step pool stream system within a larger 14 km2 catchment, which drains into the East Ovens River in SE Australia. Sediment delivery from debris flows was modelled and downstream deposition of sediment was measured using a combination of aerial imagery and field surveys. Particle size distributions were measured for all major deposits. These data were summarised to map sediment flux as a continuous variable over the drainage network. Total deposition throughout the stream network was 39 x 103 m3. Catchment efflux was 61 x 103 m3 (specific sediment yield of 78 ton ha-1), which equates to 400-800 years of background erosion, based on measurements in nearby catchments. Despite the low gradient (ca. 0.1 m m-1) of the main channel there was no systematic downstream sorting in sediment deposits in the catchment. This is due to debris flow processes operating throughout the stream network, with lateral inputs sustaining the process in low gradient channels, except in the most downstream reaches where the flow transitioned towards hyper-concentrated flow. Overall, a large proportion ( 88%) of the eroded fine fraction (<63 micron) exited the catchment, when compared to the overall ratio (55%) of erosion to deposition. The geomorphic legacy of this post-wildfire event depends on scale. In the lower channels (steam order 4-5), where erosion was nearly equal to deposition, the event had no real impact on total sediment volumes stored. In upper channels (stream orders < 3) erosion was widespread but deposition rates were low. So

LEGACY - EOP Marine Debris

Data.gov (United States)

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

Benthic plastic debris in marine and fresh water environments.

Science.gov (United States)

Corcoran, Patricia L

2015-08-01

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

Rocky Planetary Debris Around Young WDs

Science.gov (United States)

Gaensicke, B.

2014-04-01

The vast majority of all known planet host stars, including the Sun, will eventually evolve into red giants and finally end their lives as white dwarfs: extremely dense Earth-sized stellar embers. Only close-in planets will be devoured during the red-giant phase. In the solar system, Mars, the asteroid belt, and all the giant planets will escape evaporation, and the same is true for many of the known exo-planets. It is hence certain that a significant fraction of the known white dwarfs were once host stars to planets, and it is very likely that many of them still have remnants of planetary systems. The detection of metals in the atmospheres of white dwarfs is the unmistakable signpost of such evolved planetary systems. The strong surface gravity of white dwarfs causes metals to sink out of the atmosphere on time-scales much shorter than their cooling ages, leading unavoidably to pristine H/He atmospheres. Therefore any metals detected in the atmosphere of a white dwarf imply recent or ongoing accretion of planetary debris. In fact, planetary debris is also detected as circumstellar dust and gas around a number of white dwarfs. These debris disks are formed from the tidal disruption of asteroids or Kuiper belt-like objects, stirred up by left-over planets, and are subsequently accreted onto the white dwarf, imprinting their abundance pattern into its atmosphere. Determining the photospheric abundances of debris-polluted white dwarfs is hence entirely analogue to the use of meteorites, "rocks that fell from the sky", for measuring the abundances of planetary material in the solar system. I will briefly review this new field of exo-planet science, and then focus on the results of a large, unbiased COS snapshot survey of relatively young ( 20-100Myr) white dwarfs that we carried out in Cycle 18/19. * At least 30% of all white dwarfs in our sample are accreting planetary debris, and that fraction may be as high as 50%. * In most cases where debris pollution is detected

Debris Flow Occurrence and Sediment Persistence, Upper Colorado River Valley, CO.

Science.gov (United States)

Grimsley, K J; Rathburn, S L; Friedman, J M; Mangano, J F

2016-07-01

Debris flow magnitudes and frequencies are compared across the Upper Colorado River valley to assess influences on debris flow occurrence and to evaluate valley geometry effects on sediment persistence. Dendrochronology, field mapping, and aerial photographic analysis are used to evaluate whether a 19th century earthen, water-conveyance ditch has altered the regime of debris flow occurrence in the Colorado River headwaters. Identifying any shifts in disturbance processes or changes in magnitudes and frequencies of occurrence is fundamental to establishing the historical range of variability (HRV) at the site. We found no substantial difference in frequency of debris flows cataloged at eleven sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but four of the five largest debris flows originated on the west side of the valley in association with the earthen ditch, while the fifth is on a steep hillslope of hydrothermally altered rock on the east side. These results suggest that the ditch has altered the regime of debris flow activity in the Colorado River headwaters as compared to HRV by increasing the frequency of debris flows large enough to reach the Colorado River valley. Valley confinement is a dominant control on response to debris flows, influencing volumes of aggradation and persistence of debris flow deposits. Large, frequent debris flows, exceeding HRV, create persistent effects due to valley geometry and geomorphic setting conducive to sediment storage that are easily delineated by valley confinement ratios which are useful to land managers.

Using Ontological Engineering to Overcome AI-ED Problems: Contribution, Impact and Perspectives

Science.gov (United States)

Mizoguchi, Riichiro; Bourdeau, Jacqueline

2016-01-01

This article reflects on the ontology engineering methodology discussed by the paper entitled "Using Ontological Engineering to Overcome AI-ED Problems" published in this journal in 2000. We discuss the achievements obtained in the last 10 years, the impact of our work as well as recent trends and perspectives in ontology engineering for…

Engineering model for low-velocity impacts of multi-material cylinder on a rigid boundary

Directory of Open Access Journals (Sweden)

Delvare F.

2012-08-01

Full Text Available Modern ballistic problems involve the impact of multi-material projectiles. In order to model the impact phenomenon, different levels of analysis can be developed: empirical, engineering and simulation models. Engineering models are important because they allow the understanding of the physical phenomenon of the impact materials. However, some simplifications can be assumed to reduce the number of variables. For example, some engineering models have been developed to approximate the behavior of single cylinders when impacts a rigid surface. However, the cylinder deformation depends of its instantaneous velocity. At this work, an analytical model is proposed for modeling the behavior of a unique cylinder composed of two different metals cylinders over a rigid surface. Material models are assumed as rigid-perfectly plastic. Differential equation systems are solved using a numerical Runge-Kutta method. Results are compared with computational simulations using AUTODYN 2D hydrocode. It was found a good agreement between engineering model and simulation results. Model is limited by the impact velocity which is transition at the interface point given by the hydro dynamical pressure proposed by Tate.

Project report for the commercial disposal of mixed low-level waste debris

Energy Technology Data Exchange (ETDEWEB)

Andrews, G.; Balls, V.; Shea, T.; Thiesen, T.

1994-05-01

This report summarizes the basis for the commercial disposal of Idaho National Engineering Laboratory (INEL) mixed low-level waste (MLLW) debris and the associated activities. Mixed waste is radioactive waste plus hazardous waste as defined by the Resource Conservation and Recovery Act (RCRA). The critical factors for this project were DOE 5820.2A exemption, contracting mechanism, NEPA documentation, sampling and analysis, time limitation and transportation of waste. This report also will provide a guide or a starting place for future use of Envirocare of Utah or other private sector disposal/treatment facilities, and the lessons learned during this project.

Project report for the commercial disposal of mixed low-level waste debris

International Nuclear Information System (INIS)

Andrews, G.; Balls, V.; Shea, T.; Thiesen, T.

1994-05-01

This report summarizes the basis for the commercial disposal of Idaho National Engineering Laboratory (INEL) mixed low-level waste (MLLW) debris and the associated activities. Mixed waste is radioactive waste plus hazardous waste as defined by the Resource Conservation and Recovery Act (RCRA). The critical factors for this project were DOE 5820.2A exemption, contracting mechanism, NEPA documentation, sampling and analysis, time limitation and transportation of waste. This report also will provide a guide or a starting place for future use of Envirocare of Utah or other private sector disposal/treatment facilities, and the lessons learned during this project

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

Directory of Open Access Journals (Sweden)

J. Blahut

2010-11-01

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

A Numerical Approach to Estimate the Ballistic Coefficient of Space Debris from TLE Orbital Data

Science.gov (United States)

Narkeliunas, Jonas

2016-01-01

theoretical simulations, even few continuous mode 10 kW ground-based lasers, focused by 1.5 m telescopes with adaptive optics, were enough to prevent significant amount of the debris collisions. Simulations were done by propagating all space objects in LEO by 1 year into the future and checking whether the probability of collision was high. For those space objects different ground-based lasers were used to divert them, afterwards collision probabilities were reevaluated. However, the actual accuracy of the LightForce software, which has been developed at NASA AmesResearch Center, depends on the veracity of the input parameters, one of which is the objects ballistic coefficient. It is a measure of bodys ability to overcome air resistance, which has a significant impact on the debris in LEO, and thus it is responsible for the shape of the trajectory of the debris. Having the exact values of the ballistic coefficient would make significantly better collision predictions, unfortunately, we do not know what are the values for most of the objects.In this research, we were working with part of LightForce code, which estimates the ballistic coefficient from ephemerides. Previously used method gave highly inaccurate values, when compared to known objects, and it needed to be changed. The goal of this work was to try out a different method of estimating the ballistic coefficient and to check whether or not it gives noticeable improvements.

Empirical closures for particulate debris bed spreading induced by gas–liquid flow

Energy Technology Data Exchange (ETDEWEB)

Basso, S., E-mail: simoneb@kth.se; Konovalenko, A.; Kudinov, P.

2016-02-15

Highlights: • Experimental study of the debris bed self-leveling phenomenon. • A scaling approach and a non-dimensional model to describe particle flow rate are proposed. • The model is validated against experiments with particles of different properties and at different gas injection conditions. - Abstract: Efficient removal of decay heat from the nuclear reactor core debris is paramount for termination of severe accident progression. One of the strategies is based on melt fragmentation, quenching and cooling in a deep pool of water under the reactor vessel. Geometrical configuration of the debris bed is among the important factors which determine possibility of removing the decay heat from the debris bed by natural circulation of the coolant. For instance, a tall mound-shape debris bed can be non-coolable, while the same debris can be coolable if spread uniformly. Decay heat generates a significant amount of thermal energy which goes to production of steam inside the debris bed. Two-phase flow escaping through the top layer of the bed becomes a source of mechanical energy which can move the particulate debris along the slope of the bed. The motion of the debris will lead to flattening of the bed. Such process is often called “self-leveling” phenomenon. Spreading of the debris bed by the self-leveling process can take significant time, depending on the initial debris bed configuration and other parameters. There is a competition between the time scales for reaching (i) a coolable configuration of the bed, and (ii) onset of dryout and re-melting of the debris. In the previous work we have demonstrated that the rate of particulate debris spreading is determined by local gas velocity and local slope angle of the bed. In this work we develop a scaling approach and a closure for prediction of debris spreading rate based on generalization of available experimental data. We demonstrate that introduced scaling criteria are universal for particles of different

Protection Spacelab from Meteoroid and Orbital Debris

Science.gov (United States)

Zheng, Shigui; Yan, Jun; Han, Zengyao

2013-08-01

As the first long-term on-orbit spacelab of China, TianGong-1 will stay aloft for 2 years. Its failure risk subjected to Meteoroid and Orbital Debris(M/OD) is hundreds of times higher than the risk of Shenzhou-5, Shenzhou-6 or Shenzhou-7, so the special M/OD protection designs have been applied. In order to reduce the penetration risk of radiator tube, the design of radiator has been modified by placing the tube at the side of radiator plate, and the new design does not affect the thermal control system without adding the mass. Secondly, Whipple structure is adopted in the two sides and front of spacecraft against M/OD impact.

Aerogels Materials as Space Debris Collectors

Directory of Open Access Journals (Sweden)

Thierry Woignier

2013-01-01

Full Text Available Material degradation due to the specific space environment becomes a key parameter for space missions. The use of large surface of brittle materials on satellites can produce, if impacted by hypervelocity particles, ejected volumes of mater 100 times higher than the impacting one. The presented work is devoted to the use of silica aerogels as passive detectors. Aerogels have been exposed to the low earth orbit of the ISS for 18 months. The study describes the aerogels process and the choice of synthesis parameters in such a way to get expected features in terms of porosity, mechanical properties, internal stresses, and transparency. Low-density aerogels (0.09 g·cm−3 have been prepared. The control of transparency necessary to see and identify particles and fragments collected is obtained using a base catalysis during gel synthesis. After return to earth, the aerogels samples have been observed using optical microscopy to detect and quantify craters on the exposed surface. First results obtained on a small part of the aerogels indicate a large number of debris collected in the materials.

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

International Nuclear Information System (INIS)

Johnson, B. C.; Melosh, H. J.; Lisse, C. M.; Chen, C. H.; Wyatt, M. C.; Thebault, P.; Henning, W. G.; Gaidos, E.; Elkins-Tanton, L. T.; Bridges, J. C.; Morlok, A.

2012-01-01

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

Coarse woody debris in undisturbed and logged forests in the eastern Brazilian Amazon.

Science.gov (United States)

Michael Keller; Michael Palace; Gregory P. Asner; Rodrigo Jr. Pereira; Jose Natalino M. Silva

2004-01-01

Coarse woody debris (CWD) is an important component of the carbon cycle in tropical forests. We measured the volume and density of fallen CWD at two sites, Cauaxi and Tapajós in the Eastern Amazon. At both sites we studied undisturbed forests (UFs) and logged forests 1 year after harvest. Conventional logging (CL) and reduced impact logging (RIL) were...

Spacecraft-plasma-debris interaction in an ion beam shepherd mission

Science.gov (United States)

Cichocki, Filippo; Merino, Mario; Ahedo, Eduardo

2018-05-01

This paper presents a study of the interaction between a spacecraft, a plasma thruster plume and a free floating object, in the context of an active space debris removal mission based on the ion beam shepherd concept. The analysis is performed with the EP2PLUS hybrid code and includes the evaluation of the transferred force and torque to the target debris, its surface sputtering due to the impinging hypersonic ions, and the equivalent electric circuit of the spacecraft-plasma-debris interaction. The electric potential difference that builds up between the spacecraft and the debris, the ion backscattering and the backsputtering contamination of the shepherd satellite are evaluated for a nominal scenario. A sensitivity analysis is carried out to evaluate quantitatively the effects of electron thermodynamics, ambient plasma, heavy species collisions, and debris position.

Recent advances in modeling landslides and debris flows

CERN Document Server

2015-01-01

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

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

Science.gov (United States)

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 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, small woody debris can also contribute to the slurrying of sediments and maintenance of debris flows in well vegetated mountainous areas and the boulders suspended in debris flows can elevate excess pore pressure and extend debris-flow mobility. The parameters, including Id, Kp, R and etc., are affected by the intrinsic properties of debris. They, therefore, can reflect the slurrying susceptibility of sediments, and can also be applied to the research on the occurrence mechanisms and risk assessment of other debris flows.

Development of a debris flow model in a geotechnical centrifuge

Science.gov (United States)

Cabrera, Miguel Angel; Wu, Wei

2013-04-01

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

Micrometeoroid and Orbital Debris (MMOD) Shield Ballistic Limit Analysis Program

Science.gov (United States)

Ryan, Shannon

2013-01-01

This software implements penetration limit equations for common micrometeoroid and orbital debris (MMOD) shield configurations, windows, and thermal protection systems. Allowable MMOD risk is formulated in terms of the probability of penetration (PNP) of the spacecraft pressure hull. For calculating the risk, spacecraft geometry models, mission profiles, debris environment models, and penetration limit equations for installed shielding configurations are required. Risk assessment software such as NASA's BUMPERII is used to calculate mission PNP; however, they are unsuitable for use in shield design and preliminary analysis studies. The software defines a single equation for the design and performance evaluation of common MMOD shielding configurations, windows, and thermal protection systems, along with a description of their validity range and guidelines for their application. Recommendations are based on preliminary reviews of fundamental assumptions, and accuracy in predicting experimental impact test results. The software is programmed in Visual Basic for Applications for installation as a simple add-in for Microsoft Excel. The user is directed to a graphical user interface (GUI) that requires user inputs and provides solutions directly in Microsoft Excel workbooks.

Investigating impact of motor oil quality on vehicles engine induced noise level

Directory of Open Access Journals (Sweden)

I. Arefian

2015-09-01

Full Text Available Introduction: Vehicle engine id one of the main sources of noise which its level is influenced by various parameters. The aim of this study was to investigate the impact of motor oils quality before and after oil change on the variability of vehicle engine induced noise level. In this study it is tried to follow-up the efficacy of motor oil quality on engines sound level. Material and Method: First, engine noise of 94 vehicles were recorded for 30 seconds before and after oil change and all the vehicles technical information including mileage, type of motor oil, and type of vehicle were registered. Following, the recorded noises were calibrated in semi-anechoic chamber and the sound pressure levels were measured with A and C-weighting network and main octav bands, using a sound level meters. The obtained results analyzed using SPSS software version 17. Results: The effects of motor oil quality on different noise levels of engines were determined and a significant reduction in noise level of vehicles engine was observed. Investigation of the relationship between mileage and motor oil quality on various engines sound level manifested that vehicles with mileage ranged 100000-150000 miles had significant reduction in their sound pressure levels in comparison with other vehicles. Conclusion: The results revealed that engine oil is among factors reducing the vehicle engine induced noise level. Moreover, the engine oil type and the vehicle mileage are key variables which determine the impact of engine oil quality on reduction of the sound level of vehicles engine.

Cooling of an internal-heated debris bed with fine particles

International Nuclear Information System (INIS)

Yang, Z.L.; Sehgal, B.R.

2001-01-01

In this paper, an analytical model on dryout heat flux of ex-vessel debris beds with fines particles under top flooding conditions has been developed. The parametric study is performed on the effect of the stratification of the debris beds on the dryout heat flux. The calculated results show that the stratification configuration of the debris beds with smaller particles and lower porosity layer resting on the top of another layer of the beds has profound effect on the dryout heat flux for the debris beds both with and without a downcomer. The enhancement of the dryout heat flux by the downcomer is significant. The efficiency of the single downcomer on the enhancement of the dryout heat flux is also analyzed. This, in general, agrees well with experimental data. The model is also employed to perform the assessment on the coolability of the ex-vessel debris bed under representative accidental conditions. One conservative case is chosen, and it is found that the downcomer could be efficient measure to cool the debris bed and hence terminate the severe accident. (authors)

Cosmic debris what it is and what we can do about it

CERN Document Server

Powell, Jonathan

2017-01-01

This book examines the mysterious and the well-studied debris in Earth’s crowded neighborhood. From orbiting comets to the workings of the Asteroid Belt, and from meteor showers to our home-grown network of orbiting satellites, the full diversity of space objects and the debris they create is explored. Powell also discusses some of the current research techniques used to find potentially harmful rogue elements, with an emphasis on keeping watch for any objects that may intersect Earth’s orbit. Such bodies also impact other worlds, and much has been learned from observing these encounters. The information in this book is intended to foster thought about the universe in which we live, but without overloading its readers with numbers and lecture-room analysis. Like a good thriller, it allows its readers to pace themselves with the story and, by the end, encourages them to draw their own conclusions.

NASA Safety Standard: Guidelines and Assessment Procedures for Limiting Orbital Debris

Science.gov (United States)

1995-01-01

Collision with orbital debris is a hazard of growing concern as historically accepted practices and procedures have allowed man-made objects to accumulate in orbit. To limit future debris generation, NASA Management Instruction (NMI) 1700.8, 'Policy to Limit Orbital Debris Generation,' was issued in April of 1993. The NMI requires each program to conduct a formal assessment of the potential to generate orbital debris. This document serves as a companion to NMI 1700.08 and provides each NASA program with specific guidelines and assessment methods to assure compliance with the NMI. Each main debris assessment issue (e.g., Post Mission Disposal) is developed in a separate chapter.

Development of anti-debris filter for WWER-440 working fuel assembly

International Nuclear Information System (INIS)

Kolosovsky, V.; Aksyonov, P.; Kukushkin, Y.; Molchanov, V.; Kolobaev, A.

2006-01-01

Mechanical damaging of the fuel rod claddings caused by debris is one of the main reasons for fuel assembly failures. The paper focuses on the program and results of experimental and design activities carried out by Russian organizations relating to the development and investigation of operational characteristics of anti-debris filters for WWER-440 working fuel assemblies. Lead working fuel assemblies equipped with anti-debris filters have been loaded in the core of Kola-2 NPP. The results obtained can be used for making the decision concerning the application of anti-debris filter for WWER-440 working fuel assemblies with the purpose of enhancing their debris-resistance properties. (authors)

Optimizing of the recycling of contaminated concrete debris. Final report

International Nuclear Information System (INIS)

Kloeckner, J.; Rasch, H.; Schloesser, K.H.; Schon, T.

1999-01-01

1. Latest research: So far concrete debris from nuclear facilities has been free released or was treated as radioactive waste. 2. Objective: The objective of this study is to develop solutions and methods for recycling concrete debris. The amount of materials used in nuclear facilities should be limited and the contamination of new materials should be avoided. 3. Methods: The status of recycling was presented using examples of operating or completed decommissioning as well as available studies and literature. The quality requirements for the production of new concrete products using recycled materials has been discussed. The expected amounts of concrete debris for the next 12 years was estimated. For the proposed recycling examples, radiological and economic aspects have been considered. 4. Results: The production of qualified concrete products from concrete debris is possible by using modified receptions. Technical regulations to this are missing. There is no need for the utilization of large amounts of concrete debris for shielding walls. For the production of new shielding-containers for radioactive waste, concrete debris can be applied. Regarding the distance to a central recycling facility the use of mobile equipment can be economical. By using the concrete for filling the cavity or space in a final storage, it is possible to dispose the whole radioactive debris. 5. Application possibilities: The use of concrete debris as an inner concrete shielding in waste-containers today is already possible. For the manufacture of qualified concrete products by using recycling products, further developments and regulations are necessary. (orig.) [de

Assessing the debris around glaciers using remote sensing and random sets

NARCIS (Netherlands)

Bandishoev, Mus; Dilo, Arta; Stein, A.; Fonte, C.C.; Goncalves, L.M.S.; Goncalves, G.

2011-01-01

Glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces. Information on the spatial distribution and spatial-temporal dynamics of debris, however, bears various kinds of uncertainties. Debris exhibits the same spectral properties as lateral and

EDDA 1.0: integrated simulation of debris flow erosion, deposition and property changes

Science.gov (United States)

Chen, H. X.; Zhang, L. M.

2015-03-01

Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA (Erosion-Deposition Debris flow Analysis), is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of the debris flow mixture determined at limit equilibrium using the Mohr-Coulomb equation is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, an adaptive time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional debris flow with constant properties and a two-dimensional dam-break water flow. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

Morphing and vectoring impacting droplets by means of wettability-engineered surfaces.

Science.gov (United States)

Schutzius, Thomas M; Graeber, Gustav; Elsharkawy, Mohamed; Oreluk, James; Megaridis, Constantine M

2014-11-13

Driven by its importance in nature and technology, droplet impact on solid surfaces has been studied for decades. To date, research on control of droplet impact outcome has focused on optimizing pre-impact parameters, e.g., droplet size and velocity. Here we follow a different, post-impact, surface engineering approach yielding controlled vectoring and morphing of droplets during and after impact. Surfaces with patterned domains of extreme wettability (high or low) are fabricated and implemented for controlling the impact process during and even after rebound--a previously neglected aspect of impact studies on non-wetting surfaces. For non-rebound cases, droplets can be morphed from spheres to complex shapes--without unwanted loss of liquid. The procedure relies on competition between surface tension and fluid inertial forces, and harnesses the naturally occurring contact-line pinning mechanisms at sharp wettability changes to create viable dry regions in the spread liquid volume. Utilizing the same forces central to morphing, we demonstrate the ability to rebound orthogonally-impacting droplets with an additional non-orthogonal velocity component. We theoretically analyze this capability and derive a We(-.25) dependence of the lateral restitution coefficient. This study offers wettability-engineered surfaces as a new approach to manipulate impacting droplet microvolumes, with ramifications for surface microfluidics and fluid-assisted templating applications.

Behavior of explosion debris clouds

International Nuclear Information System (INIS)

Anon.

1986-01-01

In the normal course of events the behavior of debris clouds created by explosions will be of little concern to the atomic energy industry. However, two situations, one of them actual and one postulated, exist where the rise and spread of explosion clouds can affect site operations. The actual occurrence would be the detonation of nuclear weapons and the resultant release and transport of radioactive debris across the various atomic energy installations. Although the activity of the diffusing cloud is not of biological concern, it may still be sufficiently above background to play havoc with the normal readings of sensitive monitoring instruments. If it were not known that these anomalous readings resulted from explosion debris, considerable time and expense might be required for on-site testing and tracing. Fortunately it is usually possible, with the use of meteorological data and forecasts, to predict when individual sites are affected by nuclear weapon debris effects. The formation rise, and diffusion of weapon clouds will be discussed. The explosion of an atomic reactor is the postulated situation. It is common practice in reactor hazard analysis to assume a combination of circumstances which might result in a nuclear incident with a release of material to the atmosphere. It is not within the scope of this report to examine the manifold plausibilities that might lead to an explosion or the possible methods of release of gaseous and/or particulates from such an occurrence. However, if the information of a cloud is assumed and some idea of its energy content is obtainable, estimates of the cloud behavior in the atmosphere can be made

Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Directory of Open Access Journals (Sweden)

An Ping Shu

2017-04-01

Full Text Available Non-homogeneous debris flows generally occur during the rainy seasons in Southwest China, and have received considerable attention in the literature. Regarding the complexity in debris flow dynamics, experimental approaches have proven to be effective in revealing the formative mechanism for debris flow, and quantifying the relations between the various influencing factors with debris-flow formation and subsequent transport processes. Therefore, a flume-based and experimental study was performed at the Debris Flow Observation and Research Station of Jiangjia Gully in Yunnan Province, to theoretically analyze favorable conditions for debris-flow formation and initial transport by selecting the median particle size d50, flow rate Q, vertical grading coefficient ψ, slopes S, and the initial soil water contents W as the five variables for investigation. To achieve this, an optimal combination of these variables was made through an orthogonal experimental design to determine their relative importance upon the occurrence and initial mobilization behavior of a debris flow and to further enhance our insight into debris-flow triggering and transport mechanisms.

Numerical modeling of the debris flows runout

Directory of Open Access Journals (Sweden)

Federico Francesco

2017-01-01

Full Text Available Rapid debris flows are identified among the most dangerous of all landslides. Due to their destructive potential, the runout length has to be predicted to define the hazardous areas and design safeguarding measures. To this purpose, a continuum model to predict the debris flows mobility is developed. It is based on the well known depth-integrated avalanche model proposed by Savage and Hutter (S&H model to simulate the dry granular materials flows. Conservation of mass and momentum equations, describing the evolving geometry and the depth averaged velocity distribution, are re-written taking into account the effects of the interstitial pressures and the possible variation of mass along the motion due to erosion/deposition processes. Furthermore, the mechanical behaviour of the debris flow is described by a recently developed rheological law, which allows to take into account the dissipative effects of the grain inelastic collisions and friction, simultaneously acting within a ‘shear layer’, typically at the base of the debris flows. The governing PDEs are solved by applying the finite difference method. The analysis of a documented case is finally carried out.

First laser measurements to space debris in Poland

Science.gov (United States)

Lejba, Paweł; Suchodolski, Tomasz; Michałek, Piotr; Bartoszak, Jacek; Schillak, Stanisław; Zapaśnik, Stanisław

2018-05-01

The Borowiec Satellite Laser Ranging station (BORL 7811, Borowiec) being a part of the Space Research Centre of the Polish Academy of Sciences (SRC PAS) went through modernization in 2014-2015. One of the main tasks of the modernization was the installation of a high-energy laser module dedicated to space debris tracking. Surelite III by Continuum is a Nd:YAG pulse laser with 10 Hz repetition rate, a pulse width of 3-5 ns and a pulse energy of 450 mJ for green (532 nm). This new laser unit was integrated with the SLR system at Borowiec performing standard satellite tracking. In 2016 BORL 7811 participated actively to the observational campaigns related to the space debris targets from LEO region managed by the Space Debris Study Group (SDSG) of the International Laser Ranging Service (ILRS). Currently, Borowiec station regularly tracks 36 space debris from the LEO regime, including typical rocket bodies (Russian/Chinese) and cooperative targets like the inactive TOPEX/Poseidon, ENVISAT, OICETS and others. In this paper the first results of space debris laser measurements obtained by the Borowiec station in period August 2016 - January 2017 are presented. The results gained by the SRC PAS Borowiec station confirm the rotation of the defunct TOPEX/Poseidon satellite which spins with a period of approximately 10 s. The novelty of this work is the presentation of the sample results of the Chinese CZ-2C R/B target (NORAD catalogue number 31114) which is equipped (probably) with retroreflectors. Laser measurements to space debris is a very desirable topic for the next years, especially in the context of the Space Surveillance and Tracking (SST) activity. Some targets are very easy to track like defunct ENVISAT or TOPEX/Poseidon. On the other hand, there is a big population of different LEO targets with different orbital and physical parameters, which are challenging for laser ranging like small irregular debris and rocket boosters.

Experimental study of self-leveling behavior in debris bed

International Nuclear Information System (INIS)

Zhang, Bin; Harada, Tetsushi; Hirahara, Daisuke; Matsumoto, Tatsuya; Morita, Koji; Fukuda, Kenji; Yamano, Hidemasa; Suzuki, Tohru; Tobita, Yoshiharu

2008-01-01

After a core disruptive accident in a sodium-cooled fast reactor, core debris may settle on locations such as within the core-support structure or in the lower inlet plenum of the reactor vessel as debris beds, as a consequence of rapid quenching and fragmentation of core materials in subcooled sodium. The particle beds that are initially of varying depth have been observed to undergo a process of self-leveling when sodium boiling occurs within the beds. The boiling is believed to provide the driven force with debris needed to overcome resisting forces. Self-leveling ability has much effect on heat-removal capability of debris beds. In the present study, characteristics of self-leveling behaviors were investigated experimentally with simulant materials. Although the decay heat from fuel debris drives the coolant boiling in reactor accident conditions, the present experiments employed depressurization boiling of water to simulate axially increasing void distribution in a debris bed, which consists of solid particles of alumina or lead with different density. The particle size (from 0.5 mm to 6 mm in diameter) and shape (spherical or non-spherical particles) were also taken as experimental parameters. A rough criteria for self-leveling occurrence is proposed and compared with the experimental results. Characteristics of the self-leveling behaviors observed are analyzed and extrapolate to reactor accident conditions. (author)

Attitude Motion of Cylindrical Space Debris during Its Removal by Ion Beam

Directory of Open Access Journals (Sweden)

Vladimir S. Aslanov

2017-01-01

Full Text Available The paper is devoted to the problem of space debris mitigation. Contactless method of the space debris deorbiting is considered. It is assumed that ion thrusters on the active spacecraft create the ion flow, which blows the debris and slows it down. The objectives of this work are the development of mathematical models and the research of space debris motion under the action of the ion flow. It is supposed that the space debris is a rigid body of a cylindrical shape. Calculation of ion beam force and torque was performed for a self-similar model of plasma plume expansion using the hypothesis of ion fully diffused reflection from a surface. A mathematical model describing plane motions of the cylindrical space debris under the influence of gravity gradient torque and the ion flux was constructed. It was shown that motion of the space debris around its center of mass has a significant effect on its removal time. Phase portraits, describing the motion of the space debris relative to its center of mass, were constructed. Comparison of the descent times in different motion modes was carried out. The results can be used to create new effective systems of large space debris removal.

Comparison of apical debris extrusion using a conventional and two rotary techniques.

Science.gov (United States)

Adl, Alireza; Sahebi, Safoora; Moazami, Fariborz; Niknam, Mahnaz

2009-01-01

Preparation techniques and instruments produce and push debris out of canals. This can induce inflammation within the periapical area. Therefore, instrumentation that causes less extrusion of debris is more desirable. The purpose of this in vitro study was to evaluate the quantity of debris extruded from the apical foramen during root canal preparation by using one hand, and two rotary instrumentation techniques. Three different groups each with 12 mesiobuccal roots of human maxillary first molar were instrumented using either step-back technique with hand instruments, FlexMaster or Mtwo rotary system. Debris extruded from the apical foramen during canal preparation was collected. The mean dry weights of debris were compared using one-way ANOVA. Step-back group had a significantly greater mean weight of debris compared to the other two groups (Pengine driven techniques were associated with less apical debris extrusion. [Iranian Endodontic Journal 2009;4(4):135-8].

Advanced diagnostics for impact-flash spectroscopy on light-gas guns.

Energy Technology Data Exchange (ETDEWEB)

Breiland, William George; Reinhart, William Dodd; Miller, Paul Albert; Brown, Justin L.; Thornhill, Tom Finley, III (,; ); Mangan, Michael A.; Shaner, Eric Arthur; Chhabildas, Lalit Chandra; Grine, Albert D.; Wanke, Michael Clement; Alexander, C. Scott

2007-03-01

This study is best characterized as new technology development for implementing new sensors to investigate the optical characteristics of a rapidly expanding debris cloud resulting from hypervelocity impact regimes of 7 to 11 km/s. Our gas guns constitute a unique test bed that match operational conditions relevant to hypervelocity impact encountered in space engagements. We have demonstrated the use of (1) terahertz sensors, (2) silicon diodes for visible regimes, (3) germanium and InGaAs sensors for the near infrared regimes, and (4) the Sandia lightning detectors which are similar to the silicon diodes described in 2. The combination and complementary use of all these techniques has the strong potential of ''thermally'' characterizing the time dependent behavior of the radiating debris cloud. Complementary spectroscopic measurements provide temperature estimates of the impact generated debris by fitting its spectrum to a blackbody radiation function. This debris is time-dependent as its transport/expansion behavior is changing with time. The rapid expansion behavior of the debris cools the cloud rapidly, changing its thermal/temperature characteristics with time. A variety of sensors that span over a wide spectrum, varying from visible regime to THz frequencies, now gives us the potential to cover the impact over a broader temporal regime starting from high pressures (Mbar) high-temperatures (eV) to low pressures (mbar) low temperatures (less than room temperature) as the debris expands and cools.

Active space debris removal—A preliminary mission analysis and design

Science.gov (United States)

Castronuovo, Marco M.

2011-11-01

The active removal of five to ten large objects per year from the low Earth orbit (LEO) region is the only way to prevent the debris collisions from cascading. Among the three orbital regions near the Earth where most catastrophic collisions are predicted to occur, the one corresponding to a sun-synchronous condition is considered the most relevant. Forty-one large rocket bodies orbiting in this belt have been identified as the priority targets for removal. As part of a more comprehensive system engineering solution, a space mission dedicated to the de-orbiting of five rocket bodies per year from this orbital regime has been designed. The selected concept of operations envisages the launch of a satellite carrying a number of de-orbiting devices, such as solid propellant kits. The satellite performs a rendezvous with an identified object and mates with it by means of a robotic arm. A de-orbiting device is attached to the object by means of a second robotic arm, the object is released and the device is activated. The spacecraft travels then to the next target. The present paper shows that an active debris removal mission capable of de-orbiting 35 large objects in 7 years is technically feasible, and the resulting propellant mass budget is compatible with many existing platforms.

A tool for rapid post-hurricane urban tree debris estimates using high resolution aerial imagery

Science.gov (United States)

Zoltan Szantoi; Sparkle L Malone; Francisco Escobedo; Orlando Misas; Scot Smith; Bon Dewitt

2012-01-01

Coastal communities in the southeast United States have regularly experienced severe hurricane impacts. To better facilitate recovery efforts in these communities following natural disasters, state and federal agencies must respond quickly with information regarding the extent and severity of hurricane damage and the amount of tree debris volume. A tool was developed...

Temporal variations in supraglacial debris distribution on Baltoro Glacier, Karakoram between 2001 and 2012

Science.gov (United States)

Gibson, Morgan J.; Glasser, Neil F.; Quincey, Duncan J.; Mayer, Christoph; Rowan, Ann V.; Irvine-Fynn, Tristram D. L.

2017-10-01

Distribution of supraglacial debris in a glacier system varies spatially and temporally due to differing rates of debris input, transport and deposition. Supraglacial debris distribution governs the thickness of a supraglacial debris layer, an important control on the amount of ablation that occurs under such a debris layer. Characterising supraglacial debris layer thickness on a glacier is therefore key to calculating ablation across a glacier surface. The spatial pattern of debris thickness on Baltoro Glacier has previously been calculated for one discrete point in time (2004) using satellite thermal data and an empirically based relationship between supraglacial debris layer thickness and debris surface temperature identified in the field. Here, the same empirically based relationship was applied to two further datasets (2001, 2012) to calculate debris layer thickness across Baltoro Glacier for three discrete points over an 11-year period (2001, 2004, 2012). Surface velocity and sediment flux were also calculated, as well as debris thickness change between periods. Using these outputs, alongside geomorphological maps of Baltoro Glacier produced for 2001, 2004 and 2012, spatiotemporal changes in debris distribution for a sub-decadal timescale were investigated. Sediment flux remained constant throughout the 11-year period. The greatest changes in debris thickness occurred along medial moraines, the locations of mass movement deposition and areas of interaction between tributary glaciers and the main glacier tongue. The study confirms the occurrence of spatiotemporal changes in supraglacial debris layer thickness on sub-decadal timescales, independent of variation in surface velocity. Instead, variation in rates of debris distribution are primarily attributed to frequency and magnitude of mass movement events over decadal timescales, with climate, regional uplift and erosion rates expected to control debris inputs over centurial to millennial timescales. Inclusion

Coupled Eulerian-Lagrangian transport of large debris by tsunamis

Science.gov (United States)

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

2016-04-01

conservativeness of the model. This way, in highly resolved meshes and high quantities of debris, the model approaches full conservativeness only if the two-way coupling feature is present, an effect that is attenuated in coarse meshes or with small debris quantities. Aknownledgements: This work was partially funded by FEDER, program COMPETE, and by national funds through the Portuguese Foundation for Science and Technology (FCT) with project RECI/ECM-HID/0371/2012. References: Baptista M.A. & Miranda, J.M. (2009) Revision of the Portuguese catalog of tsunamis. Nat. Hazards Earth Syst. Sci., 9, 25-42. Conde, D. A. S.; Baptista, M. A. V.; Sousa Oliveira, C. & Ferreira, R. M. L. (2013) A shallow-flow model for the propagation of tsunamis over complex geometries and mobile beds, Nat. Hazards Earth Syst. Sci., 13, 2533-2542. Conde, D. A. S.; Baptista, M. A. V.; Sousa Oliveira, C. & Ferreira, R. M. L. (2015) Mathematical modelling of tsunami impacts on critical infrastructures: exposure and severity associated with debris transport at Sines port. EGU General Assembly 2015, Vienna, Austria. Ferreira, R. M. L.; Franca, M. J.; Leal, J. G. & Cardoso, A. H. (2009) Mathematical modelling of shallow flows: Closure models drawn from grain-scale mechanics of sediment transport and flow hydrodynamics, Can. J. Civil. Eng., 36, 1604-1621. LeVeque, R. J., George, D. L., & Berger, M. J. (2011) Tsunami modelling with adaptively refined finite volume methods, Acta Numerica, pp. 211-289.

Space Debris Alert System for Aviation

Science.gov (United States)

Sgobba, Tommaso

2013-09-01

Despite increasing efforts to accurately predict space debris re-entry, the exact time and location of re-entry is still very uncertain. Partially, this is due to a skipping effect uncontrolled spacecraft may experience as they enter the atmosphere at a shallow angle. Such effect difficult to model depends on atmospheric variations of density. When the bouncing off ends and atmospheric re-entry starts, the trajectory and the overall location of surviving fragments can be precisely predicted but the time to impact with ground, or to reach the airspace, becomes very short.Different is the case of a functional space system performing controlled re-entry. Suitable forecasts methods are available to clear air and maritime traffic from hazard areas (so-called traffic segregation).In US, following the Space Shuttle Columbia accident in 2003, a re-entry hazard areas location forecast system was putted in place for the specific case of major malfunction of a Reusable Launch Vehicles (RLV) at re-entry. The Shuttle Hazard Area to Aircraft Calculator (SHAAC) is a system based on ground equipment and software analyses and prediction tools, which require trained personnel and close coordination between the organization responsible for RLV operation (NASA for Shuttle) and the Federal Aviation Administration. The system very much relies on the operator's capability to determine that a major malfunction has occurred.This paper presents a US pending patent by the European Space Agency, which consists of a "smart fragment" using a GPS localizer together with pre- computed debris footprint area and direct broadcasting of such hazard areas.The risk for aviation from falling debris is very remote but catastrophic. Suspending flight over vast swath of airspace for every re-entering spacecraft or rocket upper stage, which is a weekly occurrence, would be extremely costly and disruptive.The Re-entry Direct Broadcasting Alert System (R- DBAS) is an original merging and evolution of the Re

Distributed Impact Detector System (DIDS) Health Monitoring System Evaluation

Science.gov (United States)

Prosser, William H.; Madaras, Eric I.

2010-01-01

Damage due to impacts from micrometeoroids and orbital debris is one of the most significant on-orbit hazards for spacecraft. Impacts to thermal protection systems must be detected and the damage evaluated to determine if repairs are needed to allow safe re-entry. To address this issue for the International Space Station Program, Langley Research Center and Johnson Space Center technologists have been working to develop and implement advanced methods for detecting impacts and resultant leaks. LaRC funded a Small Business Innovative Research contract to Invocon, Inc. to develop special wireless sensor systems that are compact, light weight, and have long battery lifetimes to enable applications to long duration space structures. These sensor systems are known as distributed impact detection systems (DIDS). In an assessment, the NASA Engineering and Safety Center procured two prototype DIDS sensor units to evaluate their capabilities in laboratory testing and field testing in an ISS Node 1 structural test article. This document contains the findings of the assessment.

Effect of downed woody debris on small mammal anti-predator behavior.

Energy Technology Data Exchange (ETDEWEB)

Hinkleman, Travis, M.; Orrock, John, L.; Loeb, Susan, C.

2011-10-01

Anti-predator behavior can affect prey growth, reproduction, survival, and generate emergent effects in food webs. Small mammals often lower the cost of predation by altering their behavior in response to shrubs,but the importance of other microhabitat features, such as downed woody debris, for anti-predator behavior is unknown. We used givingup densities to quantify the degree to which downed woody debris alters perceived predation risk by small mammals in southeastern pineforests. We placed 14 foraging trays next to large downed woody debris,shrubs, and in open areas for 12 consecutive nights. Moon illumination, a common indicator of predation risk, led to a similar reduction in small mammal foraging in all three microhabitats (open, downed woody debris,and shrub). Small mammals perceived open microhabitats as riskier than shrub microhabitats, with downed woody debris habitats perceived as being of intermediate risk between shrub and open microhabitats. Despite the presumed benefits of the protective cover of downed woody debris, small mammals may perceive downed woody debris as a relatively risky foraging site in southeastern pine forests where the high diversity and abundance of rodent-eating snakes may provide a primary predatory threat.

Anthropogenic effect on avalanche and debris flow activity

Directory of Open Access Journals (Sweden)

S. A. Sokratov

2013-01-01

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

FTIR Analyses of Hypervelocity Impact Deposits: DebriSat Tests

Science.gov (United States)

2015-03-27

DEPT SPACE MATERIALS LABORATORY ENGINEERING & TECHNOLOGY GROUP Shant Kenderian, DIRECTOR DEPT MATERIALS PROCESSING DEPT SPACE MATERIALS LABORATORY...ENGINEERING & TECHNOLOGY GROUP © The Aerospace Corporation, 2015. All trademarks, service marks, and trade names are the property of their respective owners...mitchell.nolan.ctr@us.af.mil SECURITY CLASSIFICATION UNCLASSIFIED Brian Roebuck AEDC brian.roebuck@us.af.mil Norman Fitz-Coy University of Florida nfc

Exploiting Maximum Entropy method and ASTER data for assessing debris flow and debris slide susceptibility for the Giampilieri catchment (north-eastern Sicily, Italy).

KAUST Repository

Lombardo, Luigi; Bachofer, F.; Cama, M.; Mä rker, M.; Rotigliano, E.

2016-01-01

This study aims at evaluating the performance of the Maximum Entropy method in assessing landslide susceptibility, exploiting topographic and multispectral remote sensing predictors. We selected the catchment of the Giampilieri stream, which is located in the north-eastern sector of Sicily (southern Italy), as test site. On 1/10/2009, a storm rainfall triggered in this area hundreds of debris flow/avalanche phenomena causing extensive economical damage and loss of life. Within this area a presence-only-based statistical method was applied to obtain susceptibility models capable of distinguish future activation sites of debris flow and debris slide, which where the main source failure mechanisms for flow or avalanche type propagation. The set of predictors used in this experiment comprised primary and secondary topographic attributes, derived by processing a high resolution digital elevation model, CORINE land cover data and a set of vegetation and mineral indices obtained by processing multispectral ASTER images. All the selected data sources are dated before the disaster. A spatially random partition technique was adopted for validation, generating fifty replicates for each of the two considered movement typologies in order to assess accuracy, precision and reliability of the models. The debris slide and debris flow susceptibility models produced high performances with the first type being the best fitted. The evaluation of the probability estimates around the mean value for each mapped pixel shows an inverted relation, with the most robust models corresponding to the debris flows. With respect to the role of each predictor within the modelling phase, debris flows appeared to be primarily controlled by topographic attributes whilst the debris slides were better explained by remotely sensed derived indices, particularly by the occurrence of previous wildfires across the slope. The overall excellent performances of the two models suggest promising perspectives for

Exploiting Maximum Entropy method and ASTER data for assessing debris flow and debris slide susceptibility for the Giampilieri catchment (north-eastern Sicily, Italy).

KAUST Repository

Lombardo, Luigi

2016-07-18

This study aims at evaluating the performance of the Maximum Entropy method in assessing landslide susceptibility, exploiting topographic and multispectral remote sensing predictors. We selected the catchment of the Giampilieri stream, which is located in the north-eastern sector of Sicily (southern Italy), as test site. On 1/10/2009, a storm rainfall triggered in this area hundreds of debris flow/avalanche phenomena causing extensive economical damage and loss of life. Within this area a presence-only-based statistical method was applied to obtain susceptibility models capable of distinguish future activation sites of debris flow and debris slide, which where the main source failure mechanisms for flow or avalanche type propagation. The set of predictors used in this experiment comprised primary and secondary topographic attributes, derived by processing a high resolution digital elevation model, CORINE land cover data and a set of vegetation and mineral indices obtained by processing multispectral ASTER images. All the selected data sources are dated before the disaster. A spatially random partition technique was adopted for validation, generating fifty replicates for each of the two considered movement typologies in order to assess accuracy, precision and reliability of the models. The debris slide and debris flow susceptibility models produced high performances with the first type being the best fitted. The evaluation of the probability estimates around the mean value for each mapped pixel shows an inverted relation, with the most robust models corresponding to the debris flows. With respect to the role of each predictor within the modelling phase, debris flows appeared to be primarily controlled by topographic attributes whilst the debris slides were better explained by remotely sensed derived indices, particularly by the occurrence of previous wildfires across the slope. The overall excellent performances of the two models suggest promising perspectives for

UniSat-5: a space-based optical system for space debris monitoring

Science.gov (United States)

Di Roberto, Riccardo; Cappelletti, Chantal

2012-07-01

Micro-satellite missions, thanks to the miniaturization process of electronic components, now have a broader range of applications. Gauss Group at School of Aerospace Engineering has been a pioneer in educational micro-satellites, namely with UNISAT and EDUSAT missions. Moreover it has been long involved in space debris related studies, such as optical observations as well as mitigation. A new project is under development for a compact digital imaging system. The purpose will be in situ observation of space debris on board Unisat-5 micro-satellite. One of the key elements of observing on orbit is that many atmospheric phenomena would be avoided, such as diffraction and EM absorption. Hence images would gain more contrast and solar spectral irradiance would be higher for the whole visible spectrum Earlier limitations of power and instrument size prevented the inclusion of these payloads in educational satellite missions. The system is composed of an optical tube, a camera, C band and S band transceivers and two antennas. The system is independent from the rest of the spacecraft. The optical tube is a Schmidt-Cassegrain reflector, and the magnitude limit is 13. The camera is equipped with a panchromatic 5Mpix sensor, capable of direct video streaming, as well as local storage of recorded images. The transceivers operate on ISM 2.4GHz and 5 GHz Wi-Fi bands, and they provide stand-alone communication capabilities to the payload, and Unisat-5 OBDH can switch between the two. Both transceivers are connected to their respective custom-designed patch antenna. The ground segment is constituted of a high gain antenna dish, which will use the same transceiver on board the spacecraft as the feed, in order to establish a TCP/IP wireless link. Every component of this system is a consumer grade product. Therefore price reduction of cutting edge imaging technology now allows the use of professional instruments, that combined with the new wireless technology developed for

Engineered soil covers for management of salt impacted sites

International Nuclear Information System (INIS)

Sweeney, D.A.; Tratch, D.J.

2005-01-01

The use of engineered soil cover systems to mitigate environmental impacts from tailings and waste rock piles is becoming an accepted practice. This paper presented design concepts for soil covers related to reclamation practices in the mining industry as an effective risk management practice at salt impacted sites. Research and field programs have demonstrated that a layered engineered soil cover can reduce or eliminate infiltration. Key components of the system included re-establishing surface vegetation to balance precipitation fluxes with evapotranspiration potential, and design of a capillary break below the rooting zone to minimize deeper seated infiltration. It was anticipated that the incorporation of a vegetation cover and a capillary break would minimize infiltration into the waste rock or tailing pile and reduce the generation of acid rock drainage (ARD). Design of a layered soil cover requires the incorporation of meteorological data, moisture retention characteristics of the impacted soils, and proposed engineered cover materials. Performance of the soil cover was predicted using a finite element model combined with meteorological data from the site area, unsaturated soil properties of the parent sub-surface soils and potential covered materials. The soil cover design consisted of re-vegetation and a loose clay cover overlying a compacted till layer. The design was conducted for an off site release of salt impacted pasture land adjacent to a former highway maintenance yard. The model predicted minimal infiltration during high precipitation events and no infiltration during low precipitation events. Results indicated that the proposed soil cover would enable re-establishment of a productive agricultural ground cover, as well as minimizing the potential for additional salt migration. It was concluded that further research and development is needed to ensure that the cover system is an acceptable method for long-term risk management. 17 refs., 5 figs

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

International Nuclear Information System (INIS)

Guan Zhonghua; Yu Hongxing; Jiang Guangming

2008-01-01

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

The Impact of Teaching Communication Strategies on English Speaking of Engineering Undergraduates

Science.gov (United States)

Kongsom, Tiwaporn

2016-01-01

This study investigates the impact of teaching communication strategies on Thai engineering undergraduate students' communication strategy use and strategic competence. Fifty-seven engineering undergraduate students were taught ten communication strategies for ten weeks and responded to a self-report communication strategy questionnaire before and…

Monitoring of Wind Turbine Gearbox Condition through Oil and Wear Debris Analysis: A Full-Scale Testing Perspective

Energy Technology Data Exchange (ETDEWEB)

Sheng, Shuangwen

2016-10-01

Despite the wind industry's dramatic development during the past decade, it is still challenged by premature turbine subsystem/component failures, especially for turbines rated above 1 MW. Because a crane is needed for each replacement, gearboxes have been a focal point for improvement in reliability and availability. Condition monitoring (CM) is a technique that can help improve these factors, leading to reduced turbine operation and maintenance costs and, subsequently, lower cost of energy for wind power. Although technical benefits of CM for the wind industry are normally recognized, there is a lack of published information on the advantages and limitations of each CM technique confirmed by objective data from full-scale tests. This article presents first-hand oil and wear debris analysis results obtained through tests that were based on full-scale wind turbine gearboxes rated at 750 kW. The tests were conducted at the 2.5-MW dynamometer test facility at the National Wind Technology Center at the National Renewable Energy Laboratory. The gearboxes were tested in three conditions: run-in, healthy, and damaged. The investigated CM techniques include real-time oil condition and wear debris monitoring, both inline and online sensors, and offline oil sample and wear debris analysis, both onsite and offsite laboratories. The reported results and observations help increase wind industry awareness of the benefits and limitations of oil and debris analysis technologies and highlight the challenges in these technologies and other tribological fields for the Society of Tribologists and Lubrication Engineers and other organizations to help address, leading to extended gearbox service life.

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

International Nuclear Information System (INIS)

Park, Jong Woon; Kim, Chang Hyun

2006-01-01

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

The Incidence of Plastic Debris along Tyume River in Alice, South Africa

OpenAIRE

Mupindu Wiseman; Mangizvo Remigios Vurayayi

2012-01-01

The article is premised on the Zero Waste theory and it addresses the environmental impact of unscientific disposal of plastic debris along Tyume River in Alice Town, South Africa. The researchers confirmed that Alice community lacks awareness on plastic waste management as evidenced by inappropriate disposal of plastic waste along the river causing environmental pollution. Behavioral action is lacking and can be enhanced through environment education and economic enterprise initiatives at th...

Impact of systems biology on metabolic engineering of Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Nielsen, Jens; Jewett, Michael Christopher

2008-01-01

in the industrial application of this yeast. Developments in genomics and high-throughput systems biology tools are enhancing one's ability to rapidly characterize cellular behaviour, which is valuable in the field of metabolic engineering where strain characterization is often the bottleneck in strain development...... programmes. Here, the impact of systems biology on metabolic engineering is reviewed and perspectives on the role of systems biology in the design of cell factories are given....

Evidence of marine debris usage by the ghost crab Ocypode quadrata (Fabricius, 1787).

Science.gov (United States)

Costa, Leonardo Lopes; Rangel, Danilo Freitas; Zalmon, Ilana Rosental

2018-03-01

Sandy beaches are sites of marine debris stranding, but the interaction of beach biota with waste is poorly studied. The objective of this study was to investigate whether the ghost crab Ocypode quadrata selects marine debris by types using a non-destructive method on sandy beaches of Southeastern Brazil. We found marine debris in 7% of 1696 surveyed burrows, and the ghost crabs selectivity was mainly by soft plastic (30%), straw (11%), rope (6%) and foam (4%). Burrows with marine debris showed higher occupation rate (~68%) compared to burrows without debris (~28%), indicating that these materials may increase the capacity of ghost crabs to memorize their burrows placement (homing). The percentage of marine debris was not always related to their amount in the drift line, but ghost crabs used more debris near urbanized areas. Future studies should test whether ghost crabs are using marine debris for feeding, homing or other mechanisms. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

2012-12-10

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

Debris avalanches and debris flows transformed from collapses in the Trans-Mexican Volcanic Belt, Mexico - behavior, and implications for hazard assessment

Science.gov (United States)

Capra, L.; Macías, J. L.; Scott, K. M.; Abrams, M.; Garduño-Monroy, V. H.

2002-03-01

Volcanoes of the Trans-Mexican Volcanic Belt (TMVB) have yielded numerous sector and flank collapses during Pleistocene and Holocene times. Sector collapses associated with magmatic activity have yielded debris avalanches with generally limited runout extent (e.g. Popocatépetl, Jocotitlán, and Colima volcanoes). In contrast, flank collapses (smaller failures not involving the volcano summit), both associated and unassociated with magmatic activity and correlating with intense hydrothermal alteration in ice-capped volcanoes, commonly have yielded highly mobile cohesive debris flows (e.g. Pico de Orizaba and Nevado de Toluca volcanoes). Collapse orientation in the TMVB is preferentially to the south and northeast, probably reflecting the tectonic regime of active E-W and NNW faults. The differing mobilities of the flows transformed from collapses have important implications for hazard assessment. Both sector and flank collapse can yield highly mobile debris flows, but this transformation is more common in the cases of the smaller failures. High mobility is related to factors such as water content and clay content of the failed material, the paleotopography, and the extent of entrainment of sediment during flow (bulking). The ratio of fall height to runout distance commonly used for hazard zonation of debris avalanches is not valid for debris flows, which are more effectively modeled with the relation inundated area to failure or flow volume coupled with the topography of the inundated area.

The impact of information technology on research in science and engineering

Energy Technology Data Exchange (ETDEWEB)

Morell, J.A.

1987-01-01

There is little research on the impact of information technology (IT) on how research is carried out by scientists and engineers. This paper draws on other bodies of writings which indirectly shed light on this question. Included are: the role of calculation in research, scientific productivity, the philosophical underpinnings of science and technology, systems analysis, and the use of computer aided design in engineering. A model is developed which helps identify the types of impact that IT may have on social system and epistemological aspects of research. Factors are hypothesized which may explain why IT may have particular effects in any given research endeavor.

Predictions for shepherding planets in scattered light images of debris disks

International Nuclear Information System (INIS)

Rodigas, Timothy J.; Hinz, Philip M.; Malhotra, Renu

2014-01-01

Planets can affect debris disk structure by creating gaps, sharp edges, warps, and other potentially observable signatures. However, there is currently no simple way for observers to deduce a disk-shepherding planet's properties from the observed features of the disk. Here we present a single equation that relates a shepherding planet's maximum mass to the debris ring's observed width in scattered light, along with a procedure to estimate the planet's eccentricity and minimum semimajor axis. We accomplish this by performing dynamical N-body simulations of model systems containing a star, a single planet, and an exterior disk of parent bodies and dust grains to determine the resulting debris disk properties over a wide range of input parameters. We find that the relationship between planet mass and debris disk width is linear, with increasing planet mass producing broader debris rings. We apply our methods to five imaged debris rings to constrain the putative planet masses and orbits in each system. Observers can use our empirically derived equation as a guide for future direct imaging searches for planets in debris disk systems. In the fortuitous case of an imaged planet orbiting interior to an imaged disk, the planet's maximum mass can be estimated independent of atmospheric models.

Sampling and Analysis Plan for K Basins Debris