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Sample records for suppress fugitive dust

  1. Study on reinforcement of soil for suppressing fugitive dust by bio-cementitious material

    Science.gov (United States)

    Zhan, Qiwei; Qian, Chunxiang

    2017-06-01

    Microbial-induced reinforcement of soil, as a new green and environmental-friendly method, is being paid extensive attention to in that it has low cost, simple operation and rapid effects. In this research, reinforcement of soil for suppressing fugitive dust by bio-cementitious material was investigated. Soil cemented by bio-cementitious material had superior mechanical properties, such as hardness, compressive strength, microstructure, wind-erosion resistance, rainfall-erosion resistance and freeze-thaw resistance. The average hardness of sandy soil, floury soil and clay soil is 18.9 º, 25.2 º and 26.1 º, while average compressive strength of samples is 0.43 MPa, 0.54 MPa and 0.69 MPa, respectively; meanwhile, the average calcite content of samples is 6.85 %, 6.09 %, and 5.96 %, respectively. Compared with the original sandy soil, floury soil and clay soil, the porosity decreases by 38.5 %, 33.7 % and 29.2 %. When wind speed is 12 m/s, the mass loss of sandy soil, floury soil and clay soil cemented by bio-cementitious material are all less than 30 g/(m2·h). After three cycles of rainfall erosion of 2.5 mm/h, the mass loss are less than 25 g/(m2·h) and the compressive strength residual ratio are more than 98.0 %. Under 25 cycles of freeze-thaw, the mass loss ratio are less than 3.0 %.

  2. Wind tunnel tests of biodegradable fugitive dust suppressants being considered to reduce soil erosion by wind at radioactive waste construction sites

    International Nuclear Information System (INIS)

    Ligotke, M.W.; Dennis, G.W.; Bushaw, L.L.

    1993-10-01

    Wind tunnel tests were performed of three fugitive dust control agents derived from potato and sugar beet products. These materials are being considered for use as dust suppressants to reduce the potential for transport of radioactive materials by wind from radioactive waste construction and remediation sites. Soil and dust control agent type, solution concentrations, application quantities, aging (or drying) conditions, surface disturbance, and wind and saltating sand eolian erosive stresses were selected and controlled to simulate application and exposure of excavated soil surfaces in the field. A description of the tests, results, conclusions, and recommendations are presented in this report. The results of this study indicate that all three dust control agents can protect exposed soil surfaces from extreme eolian stresses. It is also clear that the interaction and performance of each agent with various soil types may differ dramatically. Thus, soils similar to that received from ML should be best protected by high concentration (∼2.5%) solutions of potato starch at low water application levels (∼1 to 2 L/m 2 ). Because the effectiveness of PS on this soil type is degraded after a moderate amount of simulated rainfall, other options or additives should be considered if surfaces are to be protected for long intervals or during periods of intermittent rainfall and hot, windy conditions. On the other hand, XDCA should be considered when excavating sandy soils. It should be noted, however, that because the Hanford soil test results are based on a small number of tests, it would be prudent to perform additional tests prior to selecting a fugitive dust control agent for use at the Hanford Site. While fermented potato waste was not the best fixative used on either soil, it did perform reasonably well on both soil types (better than XDCA on Idaho soil and better than PS on Hanford soil)

  3. Estimation of fugitive dust emissions in opencast mines

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, M. [MECON Ltd., Ranchi (India). Environmental Engineering Division

    2001-02-01

    Fugitive dusts being the most annoying air pollutant in opencast mines, estimation of the fugitive dust level at ongoing sites and also prediction of dust level for the future years is important. A rapid increase in the percentage of surface mining to support an optimistic industrial growth rate at core sector has raised alarms owing to the apprehension of phenomenal increase of dust level in mine air. Fairly accurate estimation of dust dispersion level is a prerequisite to designing adequacy and suitability of a dedusting system. Determination of emission factors suited to various geomining conditions is an important basic step towards this direction. In advanced countries research work has been carried out at the national level to evolve emission factors in mining and industry. Till now no concerted effort has been attempted in India for this. In the present paper the author has utilised limited data to discuss fugitive dust emission factors for various operations for mining. 9 refs., 2 tabs.

  4. Review of fugitive dust control for uranium mill tailings

    International Nuclear Information System (INIS)

    Li, C.T.; Elmore, M.R.; Hartley, J.N.

    1983-01-01

    An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques

  5. Review of fugitive dust control for uranium mill tailings

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.T.; Elmore, M.R.; Hartley, J.N.

    1983-01-01

    An immediate concern associated with the disposal of uranium mill tailings is that wind erosion of the tailings from an impoundment area will subsequently deposit tailings on surrounding areas. Pacific Northwest Laboratory (PNL), under contract to the U.S. Nuclear Regulatory Commission, is investigating the current technology for fugitive dust control. Different methods of fugitive dust control, including chemical, physical, and vegetative, have been used or tested on mill tailings piles. This report presents the results of a literature review and discussions with manufacturers and users of available stabilization materials and techniques.

  6. Controlling fugitive dust emissions in material handling operations

    Energy Technology Data Exchange (ETDEWEB)

    Tooker, G E

    1992-05-01

    The primary mechanism of fugitive dust generation in bulk material handling transfer operations is by dispersion of dust in turbulent air induced to flow with falling or projected material streams. This paper returns to basic theories of particle dynamics and fluid mechanics to quantify the dust generating mechanism by rational analysis. Calculations involving fluid mechanisms are made easier by the availability of the personal computer and the many math manipulating programs. Rational analysis is much more cost effective when estimating collection air volumes to control fugitive emissions; especially in enclosed material handling transfers transporting large volumes of dusty material. Example calculations, using a typical enclosed conveyor-to-conveyor transfer operation are presented to illustrate and highlight the key parameters that determine the magnitude of induced air flow that must be controlled. The methods presented in this paper for estimating collection air volumes apply only enclosed material handling transfers, exhausted to a dust collector. Since some assistance to the control of dust emissions must be given by the material handling transfer chute design, a discussion of good transfer chute design practice is presented. 4 refs., 2 figs., 2 tabs.

  7. Mine haul road fugitive dust emission and exposure characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, R.J.; Visser, A.T. [University of Pretoria, Pretoria (South Africa). Dept. of Mining Engineering

    2001-03-01

    Excessive dust generation from mine haul roads is a problem common to most surface coal mining operations. Optimal wearing course material selection parameters reduce, but do not toally eliminate the potential to produce dust. For existing operations, which may not have optimally designed and maintained roads, the problem of identifying the haul road dust defect, quantifying its impact on both safety and health and assigning priorities within the constraints of limited capital and manpower is problematic. This is reflected in the fact that most surface mine operators agree dust-free roads are desirable, but find it difficult to translate this into cost-effective betterment activities. The aim of this paper is to describe fugitive dust emission and exposure characteristics associated with ultra-heavy mine haul trucks running on unpaved mine haul roads. Models are described which enable mines to assess the likely dustiness of their chosen haul road material as a function of surface loading of fines, traffic types and volume, together with various material parameters. By combining these models with the results of quantitative exposure profiling, a mine can, in conjunction with the assessment, determine the most cost- and safety-effective haul road dust management strategy. 18 refs., 10 figs., 2 tabs.

  8. 40 CFR 63.545 - Standards for fugitive dust sources.

    Science.gov (United States)

    2010-07-01

    ... storage piles, wet suppression applied to storage piles with sufficient frequency and quantity to prevent...) Materials storage and handling area—partial enclosure of storage piles, wet suppression applied to storage piles with sufficient frequency and quantity to prevent the formation of dust, vehicle wash at each exit...

  9. Numerical Validation of a Near-Field Fugitive Dust Model for Vehicles Moving on Unpaved Surfaces

    Science.gov (United States)

    2013-09-25

    turbulent dissipation rate 1 Introduction Particles suspended in air by vehicular movement on paved and unpaved roads are a major contributor to fugitive...own “ Brownian Motion” type of trajectory, but a group of particles in the same region of space do not follow the same “eddy” and the overall effects...fugitive dust caused by vehicle movement , especially when traveling on unpaved surfaces. Given the needs for particle emission models, there are very

  10. [Characteristics of fugitive dust emission from paved road near construction activities].

    Science.gov (United States)

    Tian, Gang; Fan, Shou-Bin; Li, Gang; Qin, Jian-Ping

    2007-11-01

    Because of the mud/dirt carryout from construction activities, the silt loading of paved road nearby is higher and the fugitive dust emission is stronger. By sampling and laboratory analysis of the road surface dust samples, we obtain the silt loading (mass of material equal to or less than 75 micromaters in physical diameter per unit area of travel surface) of paved roads near construction activities. The result show that silt loading of road near construction activities is higher than "normal road", and silt loading is negatively correlated with length from construction's door. According to AP-42 emission factor model of fugitive dust from roads, the emission factor of influenced road is 2 - 10 times bigger than "normal road", and the amount of fugitive dust emission influenced by one construction activity is "equivalent" to an additional road length of approximately 422 - 3 800 m with the baseline silt loading. Based on the spatial and temporal distribution of construction activities, in 2002 the amount of PM10 emission influenced by construction activities in Beijing city areas account of for 59% of fugitive dust from roads.

  11. Ensemble classification for identifying neighbourhood sources of fugitive dust and associations with observed PM10

    CSIR Research Space (South Africa)

    Khuluse-Makhanya, Sibusisiwe A

    2017-10-01

    Full Text Available accuracy of 78%. Next, cluster analysis and a varying intercepts regression model are used to assess the statistical association between land cover, a fugitive dust emissions proxy and observed PM10. We found that land cover patterns in the neighbourhood...

  12. 40 CFR 63.1445 - What work practice standards must I meet for my fugitive dust sources?

    Science.gov (United States)

    2010-07-01

    ...) Each transfer point in conveying systems used to transport fugitive dust materials. These points include, but are not limited to, transfer of material from one conveyor belt to another and transfer of...

  13. [Influence of traffic restriction on road and construction fugitive dust].

    Science.gov (United States)

    Tian, Gang; Li, Gang; Qin, Jian-Ping; Fan, Shou-Bin; Huang, Yu-Hu; Nie, Lei

    2009-05-15

    By monitoring the road and construction dust fall continuously during the "Good Luck Beijing" sport events, the reduction of road and construction dust fall caused by traffic restriction was studied. The contribution rate of road and construction dust to particulate matter of Beijing atmosphere environment, and the emission ratio of it to total local PM10 emission were analyzed. The results show that the traffic restriction reduces road and construction dust fall significantly. The dust fall average value of ring roads was 0.27 g x (m2 x d)(-1) in the "traffic restriction" period, and the values were 0.81 and 0.59 g x (m2 x d)(-1) 1 month and 7 days before. The dust fall average value of major arterial and minor arterial was 0.21 g x (m2 x d)(-1) in the "traffic restriction" period, and the values were 0.54 and 0.58 g x (m2 x d)(-1) 1 month and 7 days before. The roads emission reduced 60%-70% compared with before traffic restriction. The dust fall average values of civil architecture and utility architecture were 0.61 and 1.06 g x (m2 x d)(-1) in the "traffic restriction" period, and the values were 1.15 and 1.55 g x (m2 x d)(-1) 20 days before. The construction dust reduced 30%-47% compared with 20 days before traffic restriction. Road and construction dust emission are the main source of atmosphere particulate matter in Beijing, and its contribution to ambient PM10 concentration is 21%-36%. PM10 emitted from roads and constructions account for 42%-72% and 30%-51% of local emission while the local PM10 account for 50% and 70% of the total emission.

  14. Fugitive dust control experiments using soil fixatives on vehicle traffic surfaces

    International Nuclear Information System (INIS)

    Winberg, M.R.; Wixom, V.E.

    1992-08-01

    This report presents the results of engineering scale dust control experiments using soil fixative for contamination control during handling of transuranic waste. These experiments focused on controlling dust during retrieval operations of buried waste where waste and soil are intimately mixed. Sources of dust generation during retrieval operations include digging, dumping, and vehicle traffic. Because contaminants are expected to attach to soil particles and move with the generated dust, control of the dust spread may be the key to contamination control. Dust control techniques examined in these experiments include the use of soil fixatives to control generation of fugitive dusts during vehicle traffic operations. Previous experiments conducted in FY 1990 included testing of the soil fixative, ENTAC. These experiments showed that ENTAC was effective in controlling dust generation but had several undesirable properties such as slow cure times and clogged the pumps and application nozzles. Therefore, other products would have to be evaluated to find a suitable candidate. As a result, two soil fixatives were tested in these present experiments, COHEREX-PM, an asphalt emulsion product manufactured by Witco Corporation and FLAMBINDER, a calcium lignosulfonate product manufactured by Flambeau Corporation. The results of the experiments include product performance and recommended application methods for application in a field deployable contamination control unit to be built in FY 1993

  15. Soil sample collection and analysis for the Fugitive Dust Characterization Study

    Science.gov (United States)

    Ashbaugh, Lowell L.; Carvacho, Omar F.; Brown, Michael S.; Chow, Judith C.; Watson, John G.; Magliano, Karen C.

    A unique set of soil samples was collected as part of the Fugitive Dust Characterization Study. The study was carried out to establish whether or not source profiles could be constructed using novel analytical methods that could distinguish soil dust sources from each other. The soil sources sampled included fields planted in cotton, almond, tomato, grape, and safflower, dairy and feedlot facilities, paved and unpaved roads (both urban and rural), an agricultural staging area, disturbed land with salt buildup, and construction areas where the topsoil had been removed. The samples were collected using a systematic procedure designed to reduce sampling bias, and were stored frozen to preserve possible organic signatures. For this paper the samples were characterized by particle size (percent sand, silt, and clay), dry silt content (used in EPA-recommended fugitive dust emission factors), carbon and nitrogen content, and potential to emit both PM 10 and PM 2.5. These are not the "novel analytical methods" referred to above; rather, it was the basic characterization of the samples to use in comparing analytical methods by other scientists contracted to the California Air Resources Board. The purpose of this paper is to document the methods used to collect the samples, the collection locations, the analysis of soil type and potential to emit PM 10, and the sample variability, both within field and between fields of the same crop type.

  16. Center for Corporate Climate Leadership: Direct Fugitive Emissions from Refrigeration, Air Conditioning, Fire Suppression, and Industrial Gases

    Science.gov (United States)

    This guidance document focuses on several fugitive emissions sources that are common for organizations in many sectors: refrigeration and air conditioningsystems, fire suppression systems, and the purchase and release of industrial gases.

  17. A portable scanning lidar for real-time detection of fugitive dust emissions from multisource facilities

    Energy Technology Data Exchange (ETDEWEB)

    Emmitt, G.D. [Simpson Weather Associates, Inc., Charlottesville, VA (United States)

    1994-12-31

    A 400 mj, incoherent, pulsed, scanning CO{sub 2} lidar referred to as the Portable Laser for Coal Emission Mapping (PLACEM) is combined with a real-time version of EPA`s Industrial Source Complex - Short Term (ISCST) model to map TSP concentrations and dry deposition of fugitive particulate emissions from multiple sources within a coal handling complex. A Simpson Weather Associates concept, funded by Pier IX (a subsidiary of Zeigler Coal Handling Company), PLACEM was developed in response to the need for an eye-safe laser technique for (1) assessing the relative contribution of intermittent dust generating activities and sources within a coal transshipment facility, (2) evaluating the efficiency of various dust control measures, and (3) developing a means to assess compliance with pending Clean Air Act (CAA, 1990) regulations requiring Continuous Emission Monitoring (CEM). Integration of the PLACEM observations with the ISCST2 provides a means of dynamically calibrating the model for use with conventional in situ particulate monitors. Both simulated and real observations are presented to demonstrate the viability and utility of this lidar/model approach to fugitive emission monitoring.

  18. Isotopically constrained lead sources in fugitive dust from unsurfaced roads in the southeast Missouri mining district

    Science.gov (United States)

    Witt, Emitt C.; Pribil, Michael; Hogan, John P; Wronkiewicz, David

    2016-01-01

    The isotopic composition of lead (Pb) in fugitive dust suspended by a vehicle from 13 unsurfaced roads in Missouri was measured to identify the source of Pb within an established long-term mining area. A three end-member model using 207Pb/206Pb and concentration as tracers resulted in fugitive dust samples plotting in the mixing field of well characterized heterogeneous end members. End members selected for this investigation include the 207Pb/206Pb for 1) a Pb-mixture representing mine tailings, 2) aerosol Pb-impacted soils within close proximity to the Buick secondary recycling smelter, and 3) an average of soils, rock cores and drill cuttings representing the background conditions. Aqua regia total concentrations and 207Pb/206Pb of mining area dust suggest that 35.4–84.3% of the source Pb in dust is associated with the mine tailings mixture, 9.1–52.7% is associated with the smelter mixture, and 0–21.6% is associated with background materials. Isotope ratios varied minimally within the operational phases of sequential extraction suggesting that mixing of all three Pb mixtures occurs throughout. Labile forms of Pb were attributed to all three end members. The extractable carbonate phase had as much as 96.6% of the total concentration associated with mine tailings, 51.8% associated with smelter deposition, and 34.2% with background. The next most labile geochemical phase (Fe + Mn Oxides) showed similar results with as much as 85.3% associated with mine tailings, 56.8% associated with smelter deposition, and 4.2% associated with the background soil.

  19. Trace metals in fugitive dust from unsurfaced roads in the Viburnum Trend resource mining District of Missouri--implementation of a direct-suspension sampling methodology.

    Science.gov (United States)

    Witt, Emitt C; Wronkiewicz, David J; Pavlowsky, Robert T; Shi, Honglan

    2013-09-01

    Fugitive dust from 18 unsurfaced roadways in Missouri were sampled using a novel cyclonic fugitive dust collector that was designed to obtain suspended bulk samples for analysis. The samples were analyzed for trace metals, Fe and Al, particle sizes, and mineralogy to characterize the similarities and differences between roadways. Thirteen roads were located in the Viburnum Trend (VT) mining district, where there has been a history of contaminant metal loading of local soils; while the remaining five roads were located southwest of the VT district in a similar rural setting, but without any mining or industrial process that might contribute to trace metal enrichment. Comparison of these two groups shows that trace metal concentration is higher for dusts collected in the VT district. Lead is the dominant trace metal found in VT district dusts representing on average 79% of the total trace metal concentration, and was found moderately to strongly enriched relative to unsurfaced roads in the non-VT area. Fugitive road dust concentrations calculated for the VT area substantially exceed the 2008 Federal ambient air standard of 0.15μgm(-3) for Pb. The pattern of trace metal contamination in fugitive dust from VT district roads is similar to trace metal concentrations patterns observed for soils measured more than 40years ago indicating that Pb contamination in the region is persistent as a long-term soil contaminant. Published by Elsevier Ltd.

  20. Fugitive Felons

    Data.gov (United States)

    Social Security Administration — The Fugitive Felon Reporting and Tracking System (FRATS) houses fugitive data submitted by reporters (RIDs) and warrant agencies (WAIDs). It also controls and tracks...

  1. Road fugitive dust emission characteristics in Beijing during Olympics Game 2008 in Beijing, China

    Science.gov (United States)

    Shou-bin, Fan; Gang, Tian; Gang, Li; Yu-hu, Huang; Jian-ping, Qin; Shui-yuan, Cheng

    2009-12-01

    Eighty road dust-fall (DF) monitoring sites and 14 background monitoring sites were established in the Beijing metropolitan area, and monitoring was conducted from January 2006 to December 2008. The dust-fall attributable to roads (ΔDF) showed a clear decline from 2006 to 2008. Dust-fall levels decreased across different road types from freeway > major arterial roads > minor arterial roads > collector roads > background sites. The ΔDF showed declines of 65%, 55%, 65% and 84% respectively for freeways, major arterial, minor arterial and collector roads from August 2007 to August 2008, and declines of 77%, 76%, 82% and 82% between August 2006 and August 2008. The ΔDF declined by 80%, 79%, 82% and 69% for freeways, major arterial, minor arterial and collector roads respectively between September 2007 and September 2008, and declined by 84%, 88%, 80% and 81% between September 2006 and September 2008. Eighty samples were collected in August 2007 and August 2008 and analyzed for silt loading. PM 10 emission factors and emission strengths were calculated using the AP-42 model. The silt loading reduced by 77%, 35%, 61%, 59% and 75% for freeways, major arterial, minor arterial, collector and local roads respectively. The PM 10 emission factors were reduced by 57%, 15%, 36%, 51% and 61% and the PM 10 emission strength declined by 70%, 40%, 55%, 65% and 72% for freeways, major arterial, minor arterial, collector and local roads respectively between August 2007 and August 2008. The decline is consistent with the reduction in road dust-fall.

  2. Research and development in dust and silicosis suppression

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, H

    1975-08-21

    MAK values of 4 mg/m/sup 3/ for respirable dust containing quartz and 0.15 mg/m/sup 3/ for respirable quartz dust have been established for 5 years' exposure in West German hard coal mines. Routine gravimetric measurements were introduced in 1974 and these are supplemented by the digital Tyndallometer which indicates short-term variations. Gravimetric measurements have indicated the main sources of dust and improved dust suppression measures have considerably reduced respirable dust concentrations in some cases, e.g., by seam infusion, by spraying of the face machine path and at crushers, and by dedusters on heading machines.

  3. Experience with dust suppression in mining a thick, dirty seam

    Energy Technology Data Exchange (ETDEWEB)

    Siepmann, D; Kohlhauer, H

    1975-11-20

    Dust suppression measures used when mining a thick, dirty seam are described. Dust sprays inside and outside the shearer drum helped to reduce coarse dust, but the resulting increase in moisture content of the coal limits the extent to which this method can be used. The shields were also fitted with sprays. Because of the dirt in the seam, continuous, remotely controlled deep infusion was used. This reduced the dust concentration from more than 10 mg/m/sup 3/ to between 3.9 and 6.6 mg/m/sup 3/.

  4. Organization and effectivity of works on dust suppressing in the special zone of the Chernobyl' NPP

    International Nuclear Information System (INIS)

    Shimin, S.A.; Krapchatov, V.P.; Nad''yarnykh, G.V.; Komarov, V.I.; Andreev, Yu.B.; Samojlenko, Yu.N.

    1989-01-01

    In 1988 three methods of dust suppressing were used: regular watering of roads, chemical treatment of roadsides and dusting sections of area, long-time biologochemical fixation of open sections of area, including sowing with grass and simultaneous treatment by dust-suppressing compositions. Preliminary treatment of objects by polymeric compositions was an effective action to reduce dust-raising. 3 refs.; 3 figs

  5. Estimation of efficiency of dust suppressing works at 30-km zone near the Chernobyl' NPP

    International Nuclear Information System (INIS)

    Bakin, R.I.; Tkachenko, A.V.; Sukhoruchkin, A.K.

    1989-01-01

    Data on efficiency of dust suppressing works at 30-km zone near NPP are analyzed. It is necessary: to reduce radionuclide content in the air in the spring, when the weather is dry, to conduct dust suppressing works on roads and sections of surface with nonfixed ground; in the summer, to wash roads every day. 3 figs

  6. Suppression of dust explosions and ignition spots in biomass-fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Wilen, C; Rautalin, A

    1996-12-31

    Dust explosion characteristics of forest residue dust both at normal pressure and at elevated initial pressure have been determined in previous studies. These indices give a good base for evaluating the usability of suppression systems to obtain a sufficient level of peritoneal safety in biomass fuel handling equipment. The objectives of this project were to evaluate the usability of suppression systems and to demonstrate dust explosion suppression at elevated initial pressure. Suppression tests at 1 - 20 bar pressure will be carried out in co-operation with CTDD of British Coal, Kiddy Fire Protection and Health and Safety Executive. The tests with coal and biomass dust are scheduled to be started in March 1996 in Great Britain. In the second task of the project, self-ignition properties of forest residue dust and straw dust have been measured in a flow-through system simulating slow drying of the fuel

  7. Suppression of dust explosions and ignition spots in biomass-fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Wilen, C.; Rautalin, A.

    1995-12-31

    Dust explosion characteristics of forest residue dust both at normal pressure and at elevated initial pressure have been determined in previous studies. These indices give a good base for evaluating the usability of suppression systems to obtain a sufficient level of peritoneal safety in biomass fuel handling equipment. The objectives of this project were to evaluate the usability of suppression systems and to demonstrate dust explosion suppression at elevated initial pressure. Suppression tests at 1 - 20 bar pressure will be carried out in co-operation with CTDD of British Coal, Kiddy Fire Protection and Health and Safety Executive. The tests with coal and biomass dust are scheduled to be started in March 1996 in Great Britain. In the second task of the project, self-ignition properties of forest residue dust and straw dust have been measured in a flow-through system simulating slow drying of the fuel

  8. Suppression of dust explosions and ignition spots in biomass- fired power plants

    Energy Technology Data Exchange (ETDEWEB)

    Wilen, C; Rautalin, A [VTT Energy, Espoo (Finland)

    1997-12-01

    Dust explosion characteristics of forest residue dust both at normal pressure and at elevated initial pressure have been determined in previous studies. These indices give a good base for evaluating the usability of suppression systems to obtain a sufficient level of operational safety in biomass fuel handling equipment. The objectives of this project were to evaluate the usability of suppression systems and to demonstrate dust explosion suppression at elevated initial pressure. Suppression tests at 1 - 20 bar pressure will be carried out in co-operation with CTDD of British Coal, Kiddy Fire Protection and Health and Safety Executive. The tests with coal and biomass dust are scheduled to be started in March 1996 in Great Britain. In the second task of the project, self-ignition properties of forest residue dust and straw dust have been measured in a flow-through system simulating slow drying of the fuel

  9. Comparison of conventional and bio-treated methods as dust suppressants.

    Science.gov (United States)

    Naeimi, Maryam; Chu, Jian

    2017-10-01

    Dust is an environmental, geotechnical, health, and economical hazard. Fugitive dust emanating along transportation systems such as roads, railways, and airports especially can have significant impacts on health, safety, material loss, cost of maintenance, and interfere with the facilities. Quantitative studies on the effectiveness of the proper dust palliatives and their environmental impact have been studied with a number of biological and chemical methods. The objective of this study was to establish a method for using the microbial Induced calcium carbonate precipitation (MICP) approach to reduce the percent of mass loss against erosive force of wind regarding to the concentration and characteristics of aggregate used, climate, and traffic amounts. The results of this study showed that the required precipitation for dust control of sand by 70% is less than 15 g CaCO 3 /m 2 between sand grains in bio-treated sand. The wind tunnel test results of this study also indicate that the effectiveness of the bio-treatment method for dust control depends on many variables, such as the percent of precipitated calcium carbonate and tensile strength.

  10. The quantitative studies on gas explosion suppression by an inert rock dust deposit.

    Science.gov (United States)

    Song, Yifan; Zhang, Qi

    2018-07-05

    The traditional defence against propagating gas explosions is the application of dry rock dust, but not much quantitative study on explosion suppression of rock dust has been made. Based on the theories of fluid dynamics and combustion, a simulated study on the propagation of premixed gas explosion suppressed by deposited inert rock dust layer is carried out. The characteristics of the explosion field (overpressure, temperature, flame speed and combustion rate) at different deposited rock dust amounts are investigated. The flame in the pipeline cannot be extinguished when the deposited rock dust amount is less than 12 kg/m 3 . The effects of suppressing gas explosion become weak when the deposited rock dust amount is greater than 45 kg/m 3 . The overpressure decreases with the increase of the deposited rock dust amounts in the range of 18-36 kg/m 3 and the flame speed and the flame length show the same trends. When the deposited rock dust amount is 36 kg/m 3 , the overpressure can be reduced by 40%, the peak flame speed by 50%, and the flame length by 42% respectively, compared with those of the gas explosion of stoichiometric mixture. In this model, the effective raised dust concentrations to suppress explosion are 2.5-3.5 kg/m 3 . Copyright © 2018 Elsevier B.V. All rights reserved.

  11. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: SYNTECH PRODUCTS CORPORATION'S PETROTAC

    Science.gov (United States)

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  12. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: SYNTECH PRODUCTS CORPORATION'S TECHSUPPRESS

    Science.gov (United States)

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  13. FORENSIC CRIMINOLOGY - FUGITIVE PSYCHOLOGY

    OpenAIRE

    Nyagudi, Nyagudi Musandu

    2014-01-01

    Forensic Criminology – Fugitive Psychology, 2010 Security Summit (Regional Security Exhibition & Conference ) a forum hosted by Kenya Security Industry Association, Securi Fast Trainers & Consultants, Fidelity Security Limited at Desmond Tutu Conference Centre, Nairobi Kenya from 4th-5th March, 2010  

  14. Technology Assessment of Dust Suppression Techniques Applied During Structural Demolition. Topical Report August1, 1995 - October 30, 1996

    International Nuclear Information System (INIS)

    Boudreaux, J.F.; Ebadian, M.A.; Williams, P.T.; Dua, S.K.

    1998-01-01

    Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure properly and, at the same time, minimize the amount of dust generated from a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology given site-specific conditions. Thus, the purpose of this research, which was carried out at the Hemispheric Center for Environmental Technology (HCET) at Florida International University, was to conduct an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study targeted the problem of dust suppression during the demolition of nuclear facilities. The resulting data were employed to assist in the development of mathematical correlations that can be applied to predict dust generation during structural demolition

  15. Test plan for FY-91 dust control studies

    International Nuclear Information System (INIS)

    Winberg, M.R.

    1991-03-01

    This test plan defines basic test procedures for testing commercially available vendor products as soil fixatives and dust suppression agents to determine their capability to control fugitive dust generation during transuranic waste retrieval and handling operations. A description of the test apparatus and methods are provided in this test plan. This test plan defines the sampling procedures, controls, and analytical methods for the samples collected. Data management is discussed, as well as quality assurance and safety requirements for the study. 6 refs., 5 figs

  16. Experimental coal dust suppression system installed at the Nikola Tesla thermal power plant

    Energy Technology Data Exchange (ETDEWEB)

    Guzijan, D [Rudarski Institut, Belgrade (Yugoslavia). Zavod za Ventilaciju i Tehnicku Zastitu

    1988-01-01

    Describes a project conducted at the Nikola Tesla thermal power plant by the Mining Institute of Belgrade to reduce the high levels of dust concentrations in overloading stations on coal conveyors and hoppers. A mathematical model was developed to determine the ventilation capacity required at each of the 18 overloading stations with the hoppers considered successively: empty, 1/3 full, 2/3 full and completely full. Shows how this model enabled an efficient dust suppression system to be developed and subsequently installed by the Termovent company in Belgrade using 4 axial ventilators supplied by the Ventilator Company in Zagreb. The ventilators were powered by means of 5.5 kW electric motors and provided 440 Pa pressure at 950 rpm. Gives the result of dust concentration measurements indicating that the installed system achieved the results predicted by the mathematical model and that the levels were well below the statutory limit. A description of the complete installation is included. 3 refs.

  17. Contribution of Fugitive Emissions for PM10 Concentrations in an Industrial Area of Portugal

    Science.gov (United States)

    Marta Almeida, Susana; Viana Silva, Alexandra; Garcia, Silvia; Miranda, Ana Isabel

    2013-04-01

    Significant atmospheric dust arises from the mechanical disturbance of granular material exposed to the air. Dust generated from these open sources is termed "fugitive" because it is not discharged to the atmosphere in a confined flow stream. Common sources of fugitive dust include unpaved roads, agricultural tilling operations, aggregate storage piles, heavy construction and harbor operations. The objective of this work was to identify the likeliness and extend of the PM10 limit value exceedences due to fugitive emissions in a particularly zone where PM fugitive emissions are a core of environmental concerns - Mitrena, Portugal. Mitrena, is an industrial area that coexists with a high-density urban region (Setúbal) and areas with an important environmental concern (Sado Estuary and Arrábida which belongs to the protected area Natura 2000 Network). Due to the typology of industry sited in Mitrena (e.g. power plant, paper mill, cement, pesticides and fertilized productions), there are a large uncontrolled PM fugitive emissions, providing from heavy traffic and handling and storage of raw material on uncover stockyards in the harbor and industries. Dispersion modeling was performed with the software TAPM (The Air Pollution Model) and results were mapped over the study area, using GIS (Geographic Information Systems). Results showed that managing local particles concentrations can be a frustrating affair because the weight of fugitive sources is very high comparing with the local anthropogenic stationary sources. In order to ensure that the industry can continue to meet its commitments in protecting air quality, it is essential to warrant that the characteristics of releases from all fugitive sources are fully understood in order to target future investments in those areas where maximum benefit will be achieved.

  18. Health aspects of wood particles in fugitive emission during professional exposition

    International Nuclear Information System (INIS)

    Vlckova, H.; Schwarz, M.; Lalik, V.

    2008-01-01

    Fugitive emission of wood dust can constitute serious menace to health of worker in wood industry. Present paper describes not only influence of unaccompanied wood which develops allergic reactions, respire diseases, dermatosis, cancer etc., but also additional effects of natural wood components as endotoxins, microbial spores, amoebas, fungus, animal and proteins, volatile components wood resins, respectively. (authors)

  19. Simulation of the dust suppression process with foam in the areas of belt conveyors

    Directory of Open Access Journals (Sweden)

    Bespalov Vadim

    2017-01-01

    Full Text Available The article provides the analysis of the physical essence and simulation of the process of dust retention with foam in the air of working zones of belt conveyors transporting sand, crushed stone, gravel, coal, grain. In accordance with the proposed physical-energy concept of simulation of the process of dust control its physical essence is in a deliberate sequential action on the dust particles with previously prepared by the parameters external (additional dispersed systems. Use of dust retention technology foam method provides high efficiency of reducing the concentration of dust in the air of working areas of belt conveyors, which varies in the range of 85.0–99.0 %, which provides the standard level of dust contamination (MPC in air of working areas of listed industrial sources of formation and emission of dust.

  20. Emission Inventory for Fugitive Emissions in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2007. The inventory of fugitive emissions includes CO2, CH4, N2O, NOx, CO, NMVOC, SO2, dioxin, PAH and particulate matter. In 2007 the total Danish emission of greenhouse...

  1. Recommendations for the Development of a Dust Suppressant Test Operations Procedure (TOP) Performed at the U.S. Army Yuma Proving Ground

    Science.gov (United States)

    2010-02-08

    variety of bedrock types including: igneous ( basalt , granite, and rhyolite), metamorphic (schist and gneiss), and sedimentary rocks of Quaternary...TerraLOC® Standard formulation was applied. Chemical dust suppressant formulations vary widely, to include salts, oils, fiber mixtures and synthetic

  2. Controlling fugitive emissions from mechanical seals

    International Nuclear Information System (INIS)

    Adams, W.V.

    1992-01-01

    This paper reports that enactment of the 1990 Federal Clean Air Amendments will sharply focus efforts in the process industries to reduce fugitive emissions. Moreover, state and local governments may be imposing stricter laws and regulations which will affect allowable fugitive emissions from U.S. refineries and process plants. Plants outside the U.S. have similar concerns. Clearly, mechanical seals for process pumps represent an enormous population and is one category of equipment destined for careful evaluation as a means to control fugitive emissions. Fugitive are unintentional emissions from valves, pumps, flanges, compressors, etc., as opposed to point-source emissions from stacks, vents and flares. Fugitive emissions do not occur as a part of normal plant operations, but result from the effects of: Malfunctions, Age, Lack of proper maintenance, Operator error, Improper equipment specification, Use of inferior technology, and externally caused damage

  3. Fugitive emissions from nanopowder manufacturing

    International Nuclear Information System (INIS)

    Trompetter, W. J.; Ancelet, T.; Davy, P. K.; Kennedy, J.

    2016-01-01

    In response to health and safety questions and concerns regarding particulate matter emissions from equipment used for synthesizing NiFe and TiO 2 nanopowders, a study was undertaken to assess their impact on the air quality inside and outside a laboratory where the manufacturing equipment is operated. Elemental concentrations determined by ion beam analysis (IBA) of air particulate matter (PM) samples collected hourly with a Streaker TM sampler were used to identify possible sources and estimate contributions from nanopowder production and other sources. The fugitive nanopowder emissions were the highest at the indoor sampling location when powders were being manufactured. Average fugitive emissions of 210 ng m −3 (1-h average) (maximum 2163 ng m −3 1-h average) represented 2 % (maximum 20 %) of the average PM collected (9359 ng m −3 1-h average). The measured NiFe alloy or TiO 2 PM concentrations were much smaller than the 8-h time-weighted average (TWA) workplace exposure standards (WES) for these materials (≥1,000,000 ng m −3 ). Most PM was found to be from infiltrated outdoor ambient sources. This suggests that nanopowder production in the laboratory is not likely to have adverse health effects on individuals using the equipment, although further improvements can be made to further limit exposure.Graphical abstract

  4. Fugitive emissions from nanopowder manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Trompetter, W. J., E-mail: b.trompetter@gns.cri.nz; Ancelet, T.; Davy, P. K.; Kennedy, J. [GNS Science (New Zealand)

    2016-07-15

    In response to health and safety questions and concerns regarding particulate matter emissions from equipment used for synthesizing NiFe and TiO{sub 2} nanopowders, a study was undertaken to assess their impact on the air quality inside and outside a laboratory where the manufacturing equipment is operated. Elemental concentrations determined by ion beam analysis (IBA) of air particulate matter (PM) samples collected hourly with a Streaker{sup TM} sampler were used to identify possible sources and estimate contributions from nanopowder production and other sources. The fugitive nanopowder emissions were the highest at the indoor sampling location when powders were being manufactured. Average fugitive emissions of 210 ng m{sup −3} (1-h average) (maximum 2163 ng m{sup −3} 1-h average) represented 2 % (maximum 20 %) of the average PM collected (9359 ng m{sup −3} 1-h average). The measured NiFe alloy or TiO{sub 2} PM concentrations were much smaller than the 8-h time-weighted average (TWA) workplace exposure standards (WES) for these materials (≥1,000,000 ng m{sup −3}). Most PM was found to be from infiltrated outdoor ambient sources. This suggests that nanopowder production in the laboratory is not likely to have adverse health effects on individuals using the equipment, although further improvements can be made to further limit exposure.Graphical abstract.

  5. Technology and Policy for Suppressing Grain Dust Explosions in Storage Facilities

    National Research Council Canada - National Science Library

    1995-01-01

    To ensure workplace safety, grain handling facilities engage in a variety of activities to control the accumulation of grain dust, such as good housekeeping practices, pneumatic systems, and liquid additives...

  6. Fugitive methane emissions from an agricultural biodigester

    International Nuclear Information System (INIS)

    Flesch, Thomas K.; Desjardins, Raymond L.; Worth, Devon

    2011-01-01

    The use of agricultural biodigesters provides a strategy for reducing greenhouse gas (GHG) emissions while generating energy. The GHG reduction associated with a biodigester will be affected by fugitive emissions from the facility. The objective of this study was to measure fugitive methane (CH 4 ) emissions from a Canadian biodigester. The facility uses anaerobic digestion to produce biogas from cattle manure and other organic feedstock, which is burnt to generate electricity (1 MW capacity) and heat. An inverse dispersion technique was used to calculate emissions. Fugitive emissions were related to the operating state of the biodigester, and over four seasonal campaigns the emission rate averaged 3.2, 0.8, and 26.6 kg CH 4 hr -1 for normal operations, maintenance, and flaring periods, respectively. During normal operations the average fugitive emission rate corresponded to 3.1% of the CH 4 gas production rate. -- Highlights: → Biodigesters reduce greenhouse gas emissions. → Net emission reduction affected by fugitive emissions. → Fugitive CH 4 measured at agricultural biodigester (1 MW generating capacity). → Emissions were 3.1% of gas production. → Emissions lower than assumed in carbon credit protocols.

  7. Effect of Vehicle Characteristics on Unpaved Road Dust Emissions

    National Research Council Canada - National Science Library

    Gillies, J. A; Etyemezian, V; Kuhns, H; Nikolic, D; Gillette, D. A

    2005-01-01

    This paper presents PM10 fugitive dust emission factors for a range of vehicles types and examines the influence of vehicle and wake characteristics on the strength of emissions from an unpaved road...

  8. Novel Americium Treatment Process for Surface Water and Dust Suppression Water

    International Nuclear Information System (INIS)

    Tiepel, E.W.; Pigeon, P.; Nesta, S.; Anderson, J.

    2006-01-01

    -241 contaminated pond water, surface run-off and D and D dust suppression water during the later stages of the D and D effort at Rocky Flats. This novel chemical treatment system allowed for highly efficient, high-volume treatment of all contaminated waste waters to the very low stream standard of 0.15 pCi/1 with strict compliance to the RFCA discharge criteria for release to off-site surface waters. The rapid development and implementation of the treatment system avoided water management issues that would have had to be addressed if contaminated water had remained in Pond A-4 into the Spring of 2005. Implementation of this treatment system for the Pond A-4 waters and the D and D waters from Buildings 776 and 371 enabled the site to achieve cost-effective treatment that minimized secondary waste generation, avoiding the need for expensive off-site water disposal. Water treatment was conducted for a cost of less than $0.20/gal which included all development costs, capital costs and operational costs. This innovative and rapid response effort saved the RFETS cleanup program well in excess of $30 million for the potential cost of off-site transportation and treatment of radioactive liquid waste. (authors)

  9. Dust suppression in Belgian coal mines. Situation at the beginning of 1978

    Energy Technology Data Exchange (ETDEWEB)

    Preat, B; Vanstraelen, M

    1978-01-01

    Gives a general view of dust control in Belgian mines. Statistical data are presented in tables. Prior spraying, wet cutting, and water infusion and pneumatic drills with sprays are used; in some cases, two or more of these techniques are used together in the same face. (In French and In Dutch)

  10. USE OF BIOLOGICAL ADHESIVE FOR EFFECTIVE DUST SUPPRESSION IN MINING OPERATIONS

    Directory of Open Access Journals (Sweden)

    Aleksandr Sergeevich Danilov

    2015-11-01

    Full Text Available This article explores modern methods of reclamation of lands disturbed processes of mining, based on monitoring disturbed lands using unmanned aircraft and dusty surfaces coated biologically active adhesive, biological foam. In the article new highly efficint methods of remote monitoring of environment components are considered on based of unmanned aircrafts. For monitoring, it is suggested to draw complexes based of small unmanned aircraft vehicle, equipped with special equipment (a digital camera, a thermal imaging camera, dust meter. Land reclamation on the biological stage is encouraged by using new bio-adhesives, developed on the basis of polysaccharides and various microorganisms. This composition helps reduce the consumption of fertilizers, pesticides and other components, pioneer in growing crops on dusty surfaces in the disturbed lands. As a result of such an event, dust discharge from the surface technogenic structures is reduced up to 10 times.

  11. Dust control products at Hagerman National Wildlife Refuge, Texas: environmental safety and performance

    Science.gov (United States)

    Kunz, Bethany K.; Little, Edward E.

    2015-01-01

    Controlling fugitive dust while protecting natural resources is a challenge faced by all managers of unpaved roads. Unfortunately, road managers choosing between dust control products often have little objective environmental information to aid their decisions. To address this information gap, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collaborated on a field test of three dust control products with the objectives of (a) evaluating product performance under real-world conditions, (b) verifying the environmental safety of products identified as practically nontoxic in laboratory tests, and (c) testing the feasibility of several environmental monitoring techniques for use in dust control tests. In cooperation with refuge staff and product vendors, three products (one magnesium chloride plus binder, one cellulose, and one synthetic fluid plus binder) were applied in July 2012 to replicated road sections at the Hagerman National Wildlife Refuge in Texas. These sections were monitored periodically for 12 months after application. Product performance was assessed by mobile-mounted particulate-matter meters measuring production of fugitive dust and by observations of road conditions. Environmental safety was evaluated through on-site biological observations and leaching tests with samples of treated aggregate. All products reduced dust and improved surface condition during those 12 months. Planned environmental measurements were not always compatible with day-to-day refuge management actions; this incompatibility highlighted the need for flexible biological monitoring plans. As one of the first field tests of dust suppressants that explicitly incorporated biological endpoints, this effort provides valuable information for improving field tests and for developing laboratory or semifield alternatives.

  12. Monitoring of fugitive emissions in petrochemical plant

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Rozilda F. [Companhia Petroquimica do Nordeste (COPENE), Camacari, BA (Brazil). Div. de Engenharia Ambiental

    1993-12-31

    COPENE (Petroquimica do Nordeste S/A) has been implanting a program of fugitive emissions adapted to its reality, trying to promote a continuous improvement in its employees` working conditions and in environmental protection. This paper presents the methodology for the elaboration of this program and the conclusions of some surveys which were already completed (author). 4 refs., 7 figs., 3 tabs.

  13. Monitoring of fugitive emissions in petrochemical plant

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Rozilda F [Companhia Petroquimica do Nordeste (COPENE), Camacari, BA (Brazil). Div. de Engenharia Ambiental

    1994-12-31

    COPENE (Petroquimica do Nordeste S/A) has been implanting a program of fugitive emissions adapted to its reality, trying to promote a continuous improvement in its employees` working conditions and in environmental protection. This paper presents the methodology for the elaboration of this program and the conclusions of some surveys which were already completed (author). 4 refs., 7 figs., 3 tabs.

  14. Fate of Magnesium Chloride Brine Applied to Suppress Dust from Unpaved Roads at the INEEL Subsurface Disposal Area

    International Nuclear Information System (INIS)

    Larry Hull; Carolyn Bishop

    2004-01-01

    Between 1984 and 1993, MgCl 2 brine was used to suppress dust on unpaved roads at a radioactive waste subsurface disposal area. Because Cl - might enhance corrosion of buried metals in the waste, we investigated the distribution and fate of Cl - in the vadose zone using pore water samples collected from suction lysimeters and soluble salt concentrations extracted from sediment samples. The Cl/Br mass ratio and the total dissolved Cl - concentration of pore water show that brine contamination occurs primarily within 13 m of treated roads, but can extend as much as 30 m laterally in near-surface sedimentary deposits. Within the deep vadose zone, which consists of interlayered basalt lava flows and sedimentary interbeds, brine has moved up to 110 m laterally. This lateral migration suggests formation of perched water and horizontal transport during periods of high recharge. In a few locations, brine migrated to depths of 67 m within 3 to 5 yr. Elevated Cl - concentrations were found to depths of 2 m in roadbed material. In drainage ditches along roads, where runoff accumulates and recharge of surface water is high, Cl - was flushed from the sediments in 3 to 4 yr. In areas of lower recharge, Cl - remained in the sediments after 5 yr. Vertical brine movement is directly related to surface recharge through sediments. The distribution of Cl - in pore water and sediments is consistent with estimates of vadose zone residence times and spatial distribution of surface water recharge from other investigations at the subsurface disposal area

  15. Emission inventory for fugitive emissions from fuel in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2013. The inventory of fugitive emissions includes CO2, CH4, N2O, SO2, NOx, NMVOC, CO, particulate matter, Black carbon, heavy metals, dioxin and PAHs. In 2013 the total...... Danish emission of greenhouse gasses was 54 584 Gg CO2 equivalents. Fugitive emissions from fuels account for 387 Gg CO2 equivalents or approximately 1 %. The major part of the fugitive emissions are emitted as CO2 (61 %) mainly from flaring in upstream oil and gas production. The major source...... of fugitive CH4 emission is production of oil and gas in the North Sea, refining of oil and loading of oil onto ships both offshore and onshore. The fugitive emissions of NMVOC originate for the major part from oil and gas production, loading of ships, transmission and distribution of oil, and to a less...

  16. Fugitive Dust Emissions: Development of a Real-time Monitor

    Science.gov (United States)

    2011-10-01

    mean wind speed indicate that, for a typical mean wind speed of 4.4 m/s, particles larger than about 100 μm are likely to deposit within 10 meters ...from the point of emission. Particles that are 30 to 100 μm in diameter typically deposit within a few hundred meters from the injection point...Willeke, 1990). In general, it is accepted that isoaxial and isokinetic conditions result in representative sampling of aerosol particles from most

  17. Fort Carson Fugitive Dust Generation and Transport Study: Lessons Learned.

    Science.gov (United States)

    1981-11-01

    collection, and the data 7 *11 analysis routines. A discussion of how the research results could be applied and a detailed breakdown of labor and equipment...stations at the Community Services Building No. 1526 and on Tank Table VII employed the Electronic Weather Station built by Clima - tronics Corporation of

  18. Morus alba L. suppresses the development of atopic dermatitis induced by the house dust mite in NC/Nga mice

    Science.gov (United States)

    2014-01-01

    Background Morus alba, a medicinal plant in Asia, has been used traditionally to treat diabetes mellitus and hypoglycemia. However, the effects of M. alba extract (MAE) on atopic dermatitis have not been verified scientifically. We investigated the effects of MAE on atopic dermatitis through in vitro and in vivo experiments. Methods We evaluated the effects of MAE on the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7, as well as thymus and activation-regulated chemokine (TARC/CCL17) in HaCaT cells. In an in vivo experiment, atopic dermatitis was induced by topical application of house dust mites for four weeks, and the protective effects of MAE were investigated by measuring the severity of the skin reaction on the back and ears, the plasma levels of immunoglobulin E (IgE) and histamine, and histopathological changes in the skin on the back and ears. Results MAE suppressed the production of NO and PGE2 in RAW 264.7 cells, as well as TARC in HaCaT cells, in a dose-dependent manner. MAE treatment of NC/Nga mice reduced the severity of dermatitis and the plasma levels of IgE and histamine. MAE also reduced the histological manifestations of atopic dermatitis-like skin lesions such as erosion, hyperplasia of the epidermis and dermis, and inflammatory cell infiltration in the skin on the back and ears. Conclusion Our results suggest that MAE has potent inhibitory effects on atopic dermatitis-like lesion and may be a beneficial natural resource for the treatment of atopic dermatitis. PMID:24755250

  19. MEASUREMENT OF FUGITIVE EMISSIONS AT A BIOREACTOR LANDFILL

    Science.gov (United States)

    This report focuses on three field campaigns performed in 2002 and 2003 to measure fugitive emissions at a bioreactor landfill in Louisville, KY, using an open-path Fourier transform infrared spectrometer. The study uses optical remote sensing-radial plume mapping. The horizontal...

  20. Effective mitigation efforts to reduce road dust near industrial sites: assessment by mobile pollution surveys.

    Science.gov (United States)

    DeLuca, Patrick F; Corr, Denis; Wallace, Julie; Kanaroglou, Pavlos

    2012-05-15

    Assessment of spatial variation of fugitive dust sources, particularly road dust track-out from industrial sites and its subsequent re-suspension is difficult with fixed air quality monitoring stations given their sparse distribution and the highly localized nature of road dust. Mobile monitoring was employed to measure levels of road dust in the industrial area of the City of Hamilton, Ontario, Canada. Results of this monitoring were used in a Fugitive Dust Control workshop held for local stakeholders, where fugitive dust control solutions were presented. After the workshop, the City of Hamilton and cooperative industrial groups executed enhanced street cleaning and individual industries and facilities performed on-site control activities. Post-workshop mobile air monitoring was performed for comparison to the initial values to determine effectiveness of these approaches. A regression model testing the difference pre- and post-workshop yielded a statistically significant difference in PM(10) measurements demonstrating improvement. The average value of PM(10) prior to the workshop was 114 μg/m(3). Post-workshop the average value dropped to 73 μg/m(3). Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Diffuse and fugitive emission dose assessment on the Hanford Site

    International Nuclear Information System (INIS)

    Davis, W.E.; Schmidt, J.W.; Gleckler, B.P.; Rhoads, K.

    1995-01-01

    On February 3, 1993, the US Department of Energy, Richland Operations Office (RL), received a Compliance Order and Information Request from the Director of the Air and Toxics Division of the US Environmental Protection Agency (EPA), Region 10. The Compliance Order requires RL to (1) evaluate all radionuclide emission points at the Hanford Site to determine which are subject to continuous emission measurement requirements in 40 Code of Federal Regulations (CFR) 61, Subpart H, and (2) continuously measure radionuclide emissions in accordance with 40 CFR 61.93. The Information Request requires RL to provide a written Compliance Plan to meet the requirements of the Compliance Order. The RL Compliance Plan included as one of its milestones the requirement to develop a Federal Facility Compliance Agreement (FFCA). An FFCA was negotiated between RL and the EPA, Region 10, and was entered into on February 7, 1994. One of the milestones was to provide EPA, Region 10, with a copy of the Federal Clean Air Act Title V operating air permit application and Air Emission Inventory (AEI) concurrent with its submission to the Washington State Department of Ecology. The AEI will include an assessment of the diffuse and fugitive emissions from the Hanford Site. This assessment does not identify any diffuse or fugitive emission source that would cause an effective dose equivalent greater than 0.1 mrem/yr

  2. Measurement of fugitive emissions from gas processing plants in Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, A. [Alberta Research Council, Edmonton, AB (Canada)

    2004-07-01

    This paper presents a new gas visualization camera created to detect leaks. An outline of the device's projected entry into the oil and gas industry was provided, and included: a demonstration of Differential Absorption Light Detection and Ranging (DIAL) and leak cameras to measure and reduce fugitive emissions; a comparison of DIAL measured emissions with estimated emissions; and a review of methods to measure particulate emissions. In addition, a background of gas leak visualisation technology was presented along with an an overview of DIAL and its results from sour gas plants. The results of a survey conducted in 2003 were presented, including leaks identified and repaired as well as a follow up leak survey. An analysis of pre and post-repair hydrocarbon emissions from the Deepcut area revealed a 60 per cent reduction with savings of $140,000 as well as additional savings from reduced carbon emissions. A similar survey conducted in another plant measured emissions from condensate tanks before and after cooler installation as well as from surrounding well sites, quantifying an 80 per cent reduction in methane emissions. Tasks identified for future research concerned particulate emissions and the development of Lidar methods which can currently identify particulates, but are not yet able to quantify them. Other tasks included a complete DIAL data workup and reporting; the quantification of both methane and carbon emissions reduction at a sour gas plant; a comparison of measured emissions with methods that estimate fugitives; and a complete review of particulate measurements. tabs, figs.

  3. Puff models for simulation of fugitive radioactive emissions in atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Camila P. da, E-mail: camila.costa@ufpel.edu.b [Universidade Federal de Pelotas (UFPel), RS (Brazil). Inst. de Fisica e Matematica. Dept. de Matematica e Estatistica; Pereira, Ledina L., E-mail: ledinalentz@yahoo.com.b [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil); Vilhena, Marco T., E-mail: vilhena@pq.cnpq.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Tirabassi, Tiziano, E-mail: t.tirabassi@isac.cnr.i [Institute of Atmospheric Sciences and Climate (CNR/ISAC), Bologna (Italy)

    2009-07-01

    A puff model for the dispersion of material from fugitive radioactive emissions is presented. For vertical diffusion the model is based on general techniques for solving time dependent advection-diffusion equation: the ADMM (Advection Diffusion Multilayer Method) and GILTT (Generalized Integral Laplace Transform Technique) techniques. The first one is an analytical solution based on a discretization of the Atmospheric Boundary Layer (ABL) in sub-layers where the advection-diffusion equation is solved by the Laplace transform technique. The solution is given in integral form. The second one is a well-known hybrid method that had solved a wide class of direct and inverse problems mainly in the area of Heat Transfer and Fluid Mechanics and the solution is given in series form. Comparisons between values predicted by the models against experimental ground-level concentrations are shown. (author)

  4. Puff models for simulation of fugitive radioactive emissions in atmosphere

    International Nuclear Information System (INIS)

    Costa, Camila P. da; Vilhena, Marco T.

    2009-01-01

    A puff model for the dispersion of material from fugitive radioactive emissions is presented. For vertical diffusion the model is based on general techniques for solving time dependent advection-diffusion equation: the ADMM (Advection Diffusion Multilayer Method) and GILTT (Generalized Integral Laplace Transform Technique) techniques. The first one is an analytical solution based on a discretization of the Atmospheric Boundary Layer (ABL) in sub-layers where the advection-diffusion equation is solved by the Laplace transform technique. The solution is given in integral form. The second one is a well-known hybrid method that had solved a wide class of direct and inverse problems mainly in the area of Heat Transfer and Fluid Mechanics and the solution is given in series form. Comparisons between values predicted by the models against experimental ground-level concentrations are shown. (author)

  5. Refinery evaluation of optical imaging to locate fugitive emissions.

    Science.gov (United States)

    Robinson, Donald R; Luke-Boone, Ronke; Aggarwal, Vineet; Harris, Buzz; Anderson, Eric; Ranum, David; Kulp, Thomas J; Armstrong, Karla; Sommers, Ricky; McRae, Thomas G; Ritter, Karin; Siegell, Jeffrey H; Van Pelt, Doug; Smylie, Mike

    2007-07-01

    Fugitive emissions account for approximately 50% of total hydrocarbon emissions from process plants. Federal and state regulations aiming at controlling these emissions require refineries and petrochemical plants in the United States to implement a Leak Detection and Repair Program (LDAR). The current regulatory work practice, U.S. Environment Protection Agency Method 21, requires designated components to be monitored individually at regular intervals. The annual costs of these LDAR programs in a typical refinery can exceed US$1,000,000. Previous studies have shown that a majority of controllable fugitive emissions come from a very small fraction of components. The Smart LDAR program aims to find cost-effective methods to monitor and reduce emissions from these large leakers. Optical gas imaging has been identified as one such technology that can help achieve this objective. This paper discusses a refinery evaluation of an instrument based on backscatter absorption gas imaging technology. This portable camera allows an operator to scan components more quickly and image gas leaks in real time. During the evaluation, the instrument was able to identify leaking components that were the source of 97% of the total mass emissions from leaks detected. More than 27,000 components were monitored. This was achieved in far less time than it would have taken using Method 21. In addition, the instrument was able to find leaks from components that are not required to be monitored by the current LDAR regulations. The technology principles and the parameters that affect instrument performance are also discussed in the paper.

  6. Measurement and Modeling of Fugitive Dust from Off Road DoD Activities

    Science.gov (United States)

    2017-12-08

    Tunnel L or LOC Used in statistical analyses to discern sample locations within figure-8 plots LEM Loose Erodible Material LO Location of initial...Hopkins, 1996) and CaCO3 by the method of Leo (1963). CEC was determined by sodium saturation at pH 8.2 (Sumner and Miller, 1996). A summarization...6940 4 10 83.25 1.2e-07 *** Pass 105498 35166 3 90 421.86 < 2e-16 *** Loc 10542 5271 2 20 63.23 2.3e-09 *** SoilCode:Pass 5157 430 12 90 5.16 1.7e

  7. Characterizing and Quantifying Emissions and Transport of Fugitive Dust Emissions Due to Department of Defense Activities

    Science.gov (United States)

    2015-09-19

    response to shear stress (τ, N m-2) induced by the PI-SWERL®, the viscosity of the fluid exerts a torque (N m-1) that eventually balances with τ. The...Engelbrecht et al. (2012) from CCSEM measurements, report that these silicate mineral particles are largely coated by a veneer of clay minerals and fine...content does not, by itself, contribute to the high emissions observed at YTC. The presence of high clay content can constrain the emissions by

  8. Wood Dust

    Science.gov (United States)

    Learn about wood dust, which can raise the risk of cancers of the paranasal sinuses and nasal cavity. High amounts of wood dust are produced in sawmills, and in the furniture-making, cabinet-making, and carpentry industries.

  9. Austrian emission inventory for dust

    International Nuclear Information System (INIS)

    Winiwarter, W.; Trenker, C.; Hoeflinger, W.

    2001-09-01

    For the first time, Austrian emissions of anthropogenic particulate matter emissions to the atmosphere have been estimated. Results have been reported as total suspended particles (TSP) as well as for the fractions of particles smaller than 10 μm or 2.5 μm aerodynamic diameter (PM 10 , PM 2.5 ), respectively. Base years for the inventory were 1990, 1995 and 1999. Excluded from this assessment is wind blown dust, which has been considered a natural source here. National statistics have been applied, specifically those also used previously in the Austrian air pollution inventory (OLI). Emission factors have been taken from literature compilations, only for exceptional cases specific Austrian assessments were performed or original literature on emission measurements was consulted. Resuspension of dust by road traffic emerged as the most important source. For the size fraction of PM 10 this source contributed about half of the emissions, when applying the calculation scheme by the U.S. EPA. While this scheme is widely used and well documented, its validity is currently subject of intense scientific debate. As these results do not seem to coincide with ambient air measurements, resuspension of road dust is considered separately and not now included in the national total. The sum of all other sources increases from 75,000 t of TSP in 1990 and 1995 to 77,000 t in 1999, while both PM 10 and PM 2.5 exhibit decreasing tendency (at 45,000 t and 26,000 t in 1999, respectively). The increase in TSP derives from increasing traffic and friction related emissions (tire wear, break wear), decrease of the finer particulate matter is due to reductions in firewood consumption for domestic heating. Most important source sectors are fugitive emissions from material transfer in industry as well as the building industry and the tilling of agricultural land. Common to these sources is the high uncertainty of available data. Wood combustion is the most important of the non-fugitive

  10. Highly Stretchable, Biocompatible, Striated Substrate Made from Fugitive Glue

    Directory of Open Access Journals (Sweden)

    Wei Li

    2015-06-01

    Full Text Available We developed a novel substrate made from fugitive glue (styrenic block copolymer that can be used to analyze the effects of large strains on biological samples. The substrate has the following attributes: (1 It is easy to make from inexpensive components; (2 It is transparent and can be used in optical microscopy; (3 It is extremely stretchable as it can be stretched up to 700% strain; (4 It can be micro-molded, for example we created micro-ridges that are 6 μm high and 13 μm wide; (5 It is adhesive to biological fibers (we tested fibrin fibers, and can be used to uniformly stretch those fibers; (6 It is non-toxic to cells (we tested human mammary epithelial cells; (7 It can tolerate various salt concentrations up to 5 M NaCl and low (pH 0 and high (pH 14 pH values. Stretching of this extraordinary stretchable substrate is relatively uniform and thus, can be used to test multiple cells or fibers in parallel under the same conditions.

  11. Fugitive carbon dioxide: It's not hiding in the ocean

    International Nuclear Information System (INIS)

    Kerr, R.A.

    1992-01-01

    The fugitive carbon is the difference between the 7 billion or so tons that spew as carbon dioxide from smokestacks and burning tropical forests and the 3.4 billion tons known to stay in the atmosphere. Finding the other 3 billion or 4 billion tons has frustrated researchers for the past 15 years. The oceans certainly take up some of it. Any forecast of global warming has to be based on how much of the carbon dioxide released by human activity will remain in the atmosphere, and predictions vary by 30% depending on the mix of oceanic and terrestrial processes assumed to be removing the gas. What's more, those predictions assume that the processes at work today will go on operating. But not knowing where all the carbon is going raises the unnerving possibility that whatever processes are removing it may soon fall down on the job without warning, accelerating any warming. Such concerns add urgency to the question of whether the ocean harbors the missing carbon. But there's no simple way to find out. The obvious strategy might seem to be to measure the carbon content of the ocean repeatedly to see how much it increases year by year. The trouble is that several billion tons of added carbon, though impressive on a human scale, are undetectable against the huge swings in ocean carbon that occur from season to season, year to year, and place to place

  12. Step by step in dust control

    Energy Technology Data Exchange (ETDEWEB)

    Archer, N. [Arch Environmental Equipment, Inc. (United States)

    2003-05-01

    The paper examines the different stages in identifying delegating and controlling dust before it becomes a serious problem for a facility. Material handling, processing, storage and traffic are the major dust producing sources. All industries that convey dry, light material need to install a dust control system. The confine-seal-suppress method of dust control has provided excellent results in numerous applications, only with the combination of all three will maximum dust control. When a system is properly engineered and correctly installed, meeting the EPA Government standards becomes very easy, and is necessary in to the operation of a quality facility. 5 photos.

  13. A dust-free dock

    Energy Technology Data Exchange (ETDEWEB)

    Merrion, D. [E & F Services Ltd. (United Kingdom)

    2002-10-01

    This paper describes the process of unloading coal, petcoke and other dusty products in environmentally-sensitive areas. It presents a case study of the deepwater Port of Foynes on the west coast of Ireland which imports animal feed, fertiliser, coal and cement clinker, where dockside mobile loaders (DMLs) have eliminated spillage and controlled dust, and a record case study of the Humber International Terminal in the UK, where air curtinas, dust suppression grids and EFFEX{reg_sign} filters overcome the dust problems. 2 photos.

  14. Cometary Dust

    Science.gov (United States)

    Levasseur-Regourd, Anny-Chantal; Agarwal, Jessica; Cottin, Hervé; Engrand, Cécile; Flynn, George; Fulle, Marco; Gombosi, Tamas; Langevin, Yves; Lasue, Jérémie; Mannel, Thurid; Merouane, Sihane; Poch, Olivier; Thomas, Nicolas; Westphal, Andrew

    2018-04-01

    This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth's orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System.

  15. 40 CFR 63.7291 - What work practice standards must I meet for fugitive pushing emissions if I have a by-product...

    Science.gov (United States)

    2010-07-01

    ... meet for fugitive pushing emissions if I have a by-product coke oven battery with vertical flues? 63... meet for fugitive pushing emissions if I have a by-product coke oven battery with vertical flues? (a... existing by-product coke oven battery with vertical flues. (1) Observe and record the opacity of fugitive...

  16. Global dust sources detection using MODIS Deep Blue Collection 6 aerosol products

    Science.gov (United States)

    Pérez García-Pando, C.; Ginoux, P. A.

    2015-12-01

    Our understanding of the global dust cycle is limited by a dearth of information about dust sources, especially small-scale features which could account for a large fraction of global emissions. Remote sensing sensors are the most useful tool to locate dust sources. These sensors include microwaves, visible channels, and lidar. On the global scale, major dust source regions have been identified using polar orbiting satellite instruments. The MODIS Deep Blue algorithm has been particularly useful to detect small-scale sources such as floodplains, alluvial fans, rivers, and wadis , as well as to identify anthropogenic sources from agriculture. The recent release of Collection 6 MODIS aerosol products allows to extend dust source detection to the entire land surfaces, which is quite useful to identify mid to high latitude dust sources and detect not only dust from agriculture but fugitive dust from transport and industrial activities. This presentation will overview the advantages and drawbacks of using MODIS Deep Blue for dust detection, compare to other instruments (polar orbiting and geostationary). The results of Collection 6 with a new dust screening will be compared against AERONET. Applications to long range transport of anthropogenic dust will be presented.

  17. Allergies, asthma, and dust

    Science.gov (United States)

    Reactive airway disease - dust; Bronchial asthma - dust; Triggers - dust ... Things that make allergies or asthma worse are called triggers. Dust is a common trigger. When your asthma or allergies become worse due to dust, you are ...

  18. Engineering-scale dust control experiments

    International Nuclear Information System (INIS)

    Winberg, M.R.; Pawelko, R.J.; Jacobs, N.C.; Thompson, D.N.

    1990-12-01

    This report presents the results of engineering scale dust-control experiments relating to contamination control during handling of transuranic waste. These experiments focused on controlling dust during retrieval operations of buried waste where waste and soil are intimately mixed. Sources of dust generation during retrieval operations include digging, dumping, and vehicle traffic. Because contaminants are expected to attach to soil particles and move with the generated dust, control of the dust spread may be the key to contamination control. Dust control techniques examined in these experiments include the use of misting systems, soil fixatives, and dust suppression agents. The Dryfog Ultrasonic Misting Head, manufactured by Sonics, Incorporated, and ENTAC, an organic resin derived from tree sap manufactured by ENTAC Corporation, were tested. The results of the experiments include product performance and recommended application methods. 19 figs., 7 refs., 6 tabs

  19. 40 CFR 49.126 - Rule for limiting fugitive particulate matter emissions.

    Science.gov (United States)

    2010-07-01

    ... amount of fugitive particulate matter that may be emitted from certain air pollution sources operating... minimize the accumulation of dusty materials that have the potential to become airborne, and the prompt... materials likely to become airborne. (viii) The prompt removal from paved streets of earth or other material...

  20. 77 FR 19153 - Nonpayment of Benefits to Fugitive Felons and Probation or Parole Violators

    Science.gov (United States)

    2012-03-30

    ... toll-free number, 1-800-772-1213 or TTY 1-800-325-0778, or visit our Internet site, Social Security... SOCIAL SECURITY ADMINISTRATION 20 CFR Parts 404 and 416 [Docket No. SSA 2006-0173] RIN 0960-AG12 Nonpayment of Benefits to Fugitive Felons and Probation or Parole Violators AGENCY: Social Security...

  1. 38 CFR 3.666 - Incarcerated beneficiaries and fugitive felons-pension.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Incarcerated beneficiaries and fugitive felons-pension. 3.666 Section 3.666 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation...

  2. Rebuilding conveyor transfer points to cut fugitive material and improve operations

    Energy Technology Data Exchange (ETDEWEB)

    Stahura, R P [Martin Engineering Company, Neponset, MA (USA)

    1992-10-01

    The article describes a three-part programme to control spillage and prevent fugitive material at conveyor transfer points. The three parts are: adequate belt support; the installation of a wear line inside the chute to preserve the rubber seal system; and the maintenance of an effective edge seal. The article also discusses designing for ease of maintenance. 9 figs.

  3. PROBLEMS WITH DETERMINATION OF FUGITIVE EMISSION OF POLYCYCLIC AROMATIC HYDROCARBONS FROM COKE OVEN BATTERY

    Directory of Open Access Journals (Sweden)

    Rafał Bigda

    2017-03-01

    Full Text Available Coke oven battery is complex and multifaceted facility in terms of air pollutant emissions. As far as stack or quenching tower does not cause major difficulties of emission measurement, the fugitive emission measurement from sources such as battery top elements (charging holes, ascension pipes or oven doors is still complicated and not fully solved problem. This article presents the discussion concerning main problems and errors likely to be made in particular stages of procedure of fugitive emissions characterization from coke oven battery (selection of sampling points, sampling itself, measurement of air velocity over battery top and laboratory analyses. In addition, results of concentrations measurements of selected substances characteristic for the coking process (naphthalene, anthracene, 4 PAHs and TSP originating from fugitive sources of coke oven battery and subjected to reporting under the E-PRTR are presented. The measurements were carried out on coke oven battery top in points selected on the basis of the preceding detailed air convection velocity measurements over battery top. Results of the velocity measurements were compared with results of numerical modelling using CFD software. The presented material is an attempt to cross-sectional presentation of issues related to the quantitative evaluation of fugitive emission from coke oven battery, discussed on the example of PAHs emission as a group of substances characteristic for coking of coal.

  4. OPEN PATH TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY FOR ACQUISITION OF FUGITIVE EMISSION FLUX DATA

    Science.gov (United States)

    Air pollutant emission from unconfined sources is an increasingly important environmental issue. The U.S. EPA has developed a gorund-based optical remote sensing method that enables direct measurement of fugitive emission flux from large area sources. Open-path Fourier transfor...

  5. CHARACTERIZATION OF THE FUGITIVE MERCURY EMISSIONS AT A CHLOR-ALKALI PLANT. OVERALL STUDY DESIGN

    Science.gov (United States)

    The paper discusses a detailed emissions measurement campaign that was conducted over a 9-day period within a mercury (Hg) cell chlor-alkali plant in the southeastern United States (U.S.). The principal focus of this study was to measure fugitive (non-ducted) airborne Hg emission...

  6. Advancing Knowledge on Fugitive Natural Gas from Energy Resource Development at a Controlled Release Field Observatory

    Science.gov (United States)

    Cahill, A. G.; Chao, J.; Forde, O.; Prystupa, E.; Mayer, K. U.; Black, T. A.; Tannant, D. D.; Crowe, S.; Hallam, S.; Mayer, B.; Lauer, R. M.; van Geloven, C.; Welch, L. A.; Salas, C.; Levson, V.; Risk, D. A.; Beckie, R. D.

    2017-12-01

    Fugitive gas, comprised primarily of methane, can be unintentionally released from upstream oil and gas development either at surface from leaky infrastructure or in the subsurface through failure of energy well bore integrity. For the latter, defective cement seals around energy well casings may permit buoyant flow of natural gas from the deeper subsurface towards shallow aquifers, the ground surface and potentially into the atmosphere. Concerns associated with fugitive gas release at surface and in the subsurface include contributions to greenhouse gas emissions, subsurface migration leading to accumulation in nearby infrastructure and impacts to groundwater quality. Current knowledge of the extent of fugitive gas leakage including how to best detect and monitor over time, and particularly its migration and fate in the subsurface, is incomplete. We have established an experimental field observatory for evaluating fugitive gas leakage in an area of historic and ongoing hydrocarbon resource development within the Montney Resource Play of the Western Canadian Sedimentary Basin, British Columbia, Canada. Natural gas will be intentionally released at surface and up to 25 m below surface at various rates and durations. Resulting migration patterns and impacts will be evaluated through examination of the geology, hydrogeology, hydro-geochemistry, isotope geochemistry, hydro-geophysics, vadose zone and soil gas processes, microbiology, and atmospheric conditions. The use of unmanned aerial vehicles and remote sensors for monitoring and detection of methane will also be assessed for suitability as environmental monitoring tools. Here we outline the experimental design and describe initial research conducted to develop a detailed site conceptual model of the field observatory. Subsequently, results attained from pilot surface and sub-surface controlled natural gas releases conducted in late summer 2017 will be presented as well as results of numerical modelling conducted

  7. Study on coal dust wettability measurement using cold briquetting technique

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Xu, H.; Shu, X. [North China Institute of Science and Technology, Beijing (China). Department of Resource and Environmental Engineering

    2008-12-15

    Quantitative measuring of coal dust wettability is essential for the research and development of chemical coal dust suppressants in the field of dust control with wetting-agent-added water. The causes of low repeat rate and poor consistency in present lab testing of coal dust wettability are discussed. The influence of different briquetting pressure (from 0 to 6.5108 Pa) on the wet behavior of coal dust is investigated as a new way to quantitatively evaluate coal dust wettability. The study shows that there is a fairly high coincidence between the coal dust wettability data measured by the briquetting technique and the results gained from the lab dust suppression tests using an MCYZ apparatus designed by the authors. 9 refs., 8 figs., 2 tabs.

  8. Atmospheric Fate and Transport of Agricultural Dust and Ammonia

    Science.gov (United States)

    Hiranuma, N.; Brooks, S. D.; Thornton, D. C.; Auvermann, B. W.; Fitz, D. R.

    2008-12-01

    Agricultural fugitive dust and odor are significant sources of localized air pollution in the semi-arid southern Great Plains. Daily episodes of ground-level fugitive dust emissions from the cattle feedlots associated with increased cattle activity in the early evenings are routinely observed, while consistently high ammonia is observed throughout the day. Here we present measurements of aerosol size distributions and concentrations of gas and particulate phase ammonia species collected at a feedlot in Texas during summers of 2006, 2007 and 2008. A GRIMM sequential mobility particle sizer and GRIMM 1.108 aerosol spectrometer were used to determine aerosol size distributions in the range of 10 nm to 20 µm aerodynamic diameter at the downwind and upwind edges of the facility. Using aqueous scrubbers, simultaneous measurements of both gas phase and total ammonia species present in the gas and particle phases were also collected. In addition to the continuous measurements at the edges of the facility, coincident aerosol and ammonia measurements were obtain at an additional site further downwind (~3.5 km). Taken together our measurements will be used to quantify aerosol and ammonia dispersion and transport. Relationships between the fate and transport of the aerosols and ammonia will be discussed.

  9. Determination of road dust loadings and chemical characteristics using resuspension.

    Science.gov (United States)

    Chen, Jianhua; Wang, Wei; Liu, Hongjie; Ren, Lihong

    2012-03-01

    The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM(10) and PM(2.5) from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM(10) and PM(2.5) filter samples. The average road dust loading was 3.82 g m(-2), with the highest of 24.22 g m(-2) being in Hutongs in the rural-urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural-urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM(10) and PM(2.5) in road dust. The average abundances of OC and EC in PM(10) and PM(2.5) in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM(10) and PM(2.5) resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl( - ) and Na( + ) was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater.

  10. INTELLIGENCE STUDIES IN FORENSIC CRIMINOLOGY OF FUGITIVE EMANATING DEFINITIVE AND LOCATIONAL PARAMETERS - Dissertation without Errata

    OpenAIRE

    Nyagudi, Nyagudi Musandu

    2014-01-01

    This dissertation addresses the problem of manhunts, against criminal fugitives. It establishesnew ways of describing and refining mechanisms and techniques, for manhunts. Methods used in thisdissertation to meet those objectives, include: review of case studies, benchmarking of techniques andthe analysis of techniques and concepts, which have been put forward by other scholars. Emphasishas been placed on the applicability of search techniques to a wide range of situations, and techniques for...

  11. Assessing fugitive emissions of CH4 from high-pressure gas pipelines

    Science.gov (United States)

    Worrall, Fred; Boothroyd, Ian; Davies, Richard

    2017-04-01

    The impact of unconventional natural gas production using hydraulic fracturing methods from shale gas basins has been assessed using life-cycle emissions inventories, covering areas such as pre-production, production and transmission processes. The transmission of natural gas from well pad to processing plants and its transport to domestic sites is an important source of fugitive CH4, yet emissions factors and fluxes from transmission processes are often based upon ver out of date measurements. It is important to determine accurate measurements of natural gas losses when compressed and transported between production and processing facilities so as to accurately determine life-cycle CH4 emissions. This study considers CH4 emissions from the UK National Transmission System (NTS) of high pressure natural gas pipelines. Mobile surveys of CH4 emissions using a Picarro Surveyor cavity-ring-down spectrometer were conducted across four areas in the UK, with routes bisecting high pressure pipelines and separate control routes away from the pipelines. A manual survey of soil gas measurements was also conducted along one of the high pressure pipelines using a tunable diode laser. When wind adjusted 92 km of high pressure pipeline and 72 km of control route were drive over a 10 day period. When wind and distance adjusted CH4 fluxes were significantly greater on routes with a pipeline than those without. The smallest leak detectable was 3% above ambient (1.03 relative concentration) with any leaks below 3% above ambient assumed ambient. The number of leaks detected along the pipelines correlate to the estimated length of pipe joints, inferring that there are constant fugitive CH4 emissions from these joints. When scaled up to the UK's National Transmission System pipeline length of 7600 km gives a fugitive CH4 flux of 4700 ± 2864 kt CH4/yr - this fugitive emission from high pressure pipelines is 0.016% of the annual gas supply.

  12. Localization of fugitive methane emission from natural gas distribution network of Titas Gas

    Directory of Open Access Journals (Sweden)

    Mandal Pradip C.

    2017-03-01

    Full Text Available The aim of this paper is to localize the fugitive leaks from the above ground facilities of the existing system of Titas Gas (TG after developing mathematical model for fugitive emission. Soap screening techniques and Gasurveyor 500 series instrument were used in this study for detecting potential leaks. Leaked gas was quantified using either Hi-Flow gas sampler or bagging measurements system. The results show that the respective potential gas leaking point of City Gate Station (CGS, commercial Regulating and Metering Station (RMS, industrial RMS, residential RMS and Town Bordering Station (TBS/ District Regulating Station (DRS are scrubber dump valve (average leak rate 217.00 L/min, insulating point (average leak rate 4.04 L/min, tube fitting connector (average leak rate 8.00 L/min, connector (average leak rate 1.55 L/min and pressure relief valve (average leak rate 437.92 L/min. Fugitive methane emission can be reduced by stopping leaks of fittings or components having high KLeak value.

  13. Dust emissions from unpaved roads on the Colorado Plateau

    Science.gov (United States)

    Duniway, M.; Flagg, C.; Belnap, J.

    2013-12-01

    On the Colorado Plateau, elevated levels of aeolian dust have become a major land management and policy concern due to its influence on climate, weather, terrestrial ecosystem dynamics, landscape development and fertility, melting of snow and ice, air quality, and human health. Most desert soil surfaces are stabilized by plants, rocks, and/or physical or biological soil crusts, but once disturbed, sediment production from these surfaces can increase dramatically. Road development and use is a common surface disturbing activity in the region. The extent and density of roads and road networks is rapidly increasing due to continued energy exploration, infrastructure development, and off-highway recreation activities. Though it is well known that unpaved roads produce dust, the relative contribution of dust from existing roads or the implications of future road development to regional dust loading is unknown. To address this need, we have initiated a multifaceted research effort to evaluating dust emissions from unpaved roads regionally. At 34 sites arranged across various road surfaces and soil textures in southeastern Utah, we are: 1) monitoring dust emissions, local wind conditions, and vehicle traffic and 2) evaluating fugitive dust potential using a portable wind tunnel and measuring road characteristics that affect dust production. We will then 3) develop a GIS-based model that integrates results from 1 & 2 to estimate potential dust contributions from current and future scenarios of regional road development. Passive, horizontal sediment traps were installed at three distances downwind from the road edge. One control trap was placed upwind of the samplers to account for local, non-road dust emissions. An electronic vehicle counter and anemometer were also installed at monitoring sites. Dust samples were collected every three months at fixed heights, 15 cm up to 100 cm above the soil surface, from March 2010 to the present. Threshold friction velocities (TFV

  14. Assessing fugitive emissions of CH4 from high-pressure gas pipelines in the UK

    Science.gov (United States)

    Clancy, S.; Worrall, F.; Davies, R. J.; Almond, S.; Boothroyd, I.

    2016-12-01

    Concern over the greenhouse gas impact of the exploitation of unconventional natural gas from shale deposits has caused a spotlight to be shone on to the entire hydrocarbon industry. Numerous studies have developed life-cycle emissions inventories to assess the impact that hydraulic fracturing has upon greenhouse gas emissions. Incorporated within life-cycle assessments are transmission and distribution losses, including infrastructure such as pipelines and compressor stations that pressurise natural gas for transport along pipelines. Estimates of fugitive emissions from transmission, storage and distribution have been criticized for reliance on old data from inappropriate sources (1970s Russian gas pipelines). In this study, we investigate fugitive emissions of CH4 from the UK high pressure national transmission system. The study took two approaches. Firstly, CH4 concentration is detected by driving along roads bisecting high pressure gas pipelines and also along an equivalent distance along a route where no high pressure gas pipeline was nearby. Five pipelines and five equivalent control routes were driven and the test was that CH4 measurements, when adjusted for distance and wind speed, should be greater on any route with a pipe than any route without a pipe. Secondly, 5 km of a high pressure gas pipeline and 5 km of equivalent farmland, were walked and soil gas (above the pipeline where present) was analysed every 7 m using a tunable diode laser. When wind adjusted 92 km of high pressure pipeline and 72 km of control route were drive over a 10 day period. When wind and distance adjusted CH4 fluxes were significantly greater on routes with a pipeline than those without. The smallest leak detectable was 3% above ambient (1.03 relative concentration) with any leaks below 3% above ambient assumed ambient. The number of leaks detected along the pipelines correlate to the estimated length of pipe joints, inferring that there are constant fugitive CH4 emissions from

  15. Surface renewal as a significant mechanism for dust emission

    Directory of Open Access Journals (Sweden)

    J. Zhang

    2016-12-01

    Full Text Available Wind tunnel experiments of dust emissions from different soil surfaces are carried out to better understand dust emission mechanisms. The effects of surface renewal on aerodynamic entrainment and saltation bombardment are analyzed in detail. It is found that flow conditions, surface particle motions (saltation and creep, soil dust content and ground obstacles all strongly affect dust emission, causing its rate to vary over orders of magnitude. Aerodynamic entrainment is highly effective, if dust supply is unlimited, as in the first 2–3 min of our wind tunnel runs. While aerodynamic entrainment is suppressed by dust supply limits, surface renewal through the motion of surface particles appears to be an effective pathway to remove the supply limit. Surface renewal is also found to be important to the efficiency of saltation bombardment. We demonstrate that surface renewal is a significant mechanism affecting dust emission and recommend that this mechanism be included in future dust models.

  16. Salt Efflorescence Effects on Soil Surface Erodibility and Dust Emissions

    Science.gov (United States)

    Van Pelt, R. S.; Zhang, G.

    2017-12-01

    Soluble salts resulting from weathering of geological materials often form surface crusts or efflorescences in areas with shallow saline groundwater. In many cases, the affected areas are susceptible to wind erosion due to their lack of protective vegetation and their flat topography. Fugitive dusts containing soluble salts affect the biogeochemistry of deposition regions and may result in respiratory irritation during transport. We created efflorescent crusts on soil trays by surface evaporation of single salt solutions and bombarded the resultant efflorescences with quartz abrader sand in a laboratory wind tunnel. Four replicate trays containing a Torrifluvent soil affected by one of nine salts commonly found in arid and semiarid streams were tested and the emissions were captured by an aspirated multi-stage deposition and filtering system. We found that in most cases the efflorescent crust reduced the soil surface erodibility but also resulted in the emission of salt rich dust. Two of the salts, sodium thiosulfate and calcium chloride, resulted in increased soil volume and erodibility. However, one of the calcium chloride replicates was tested after an outbreak of humid air caused hygroscopic wetting of the soil and it became indurated upon drying greatly decreasing the erodibility. Although saline affected soils are not used for agricultural production and degradation is not a great concern, the release of salt rich dust is an area of environmental concern and steps to control the dust emissions from affected soils should be developed. Future testing will utilize suites of salts found in streams of arid and semiarid regions.

  17. 40 CFR 63.7292 - What work practice standards must I meet for fugitive pushing emissions if I have a by-product...

    Science.gov (United States)

    2010-07-01

    ... meet for fugitive pushing emissions if I have a by-product coke oven battery with horizontal flues? 63... meet for fugitive pushing emissions if I have a by-product coke oven battery with horizontal flues? (a...) Prepare and operate by a written plan that will eliminate or minimize incomplete coking for each by...

  18. A new approach to estimate fugitive methane emissions from coal mining in China

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Yiwen, E-mail: juyw03@163.com [Key Laboratory of Computational Geodynamics of Chinese Academy Sciences, Beijing 100049 (China); College of Earth Science, University of Chinese Academy Sciences, Beijing 100049 (China); Sun, Yue [Key Laboratory of Computational Geodynamics of Chinese Academy Sciences, Beijing 100049 (China); College of Earth Science, University of Chinese Academy Sciences, Beijing 100049 (China); Sa, Zhanyou [Department of Safety Engineering, Qingdao Technological University, Qingdao 266520 (China); Pan, Jienan [School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454000 (China); Wang, Jilin [School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116 (China); Hou, Quanlin; Li, Qingguang; Yan, Zhifeng [Key Laboratory of Computational Geodynamics of Chinese Academy Sciences, Beijing 100049 (China); College of Earth Science, University of Chinese Academy Sciences, Beijing 100049 (China); Liu, Jie [Department of Safety Engineering, Qingdao Technological University, Qingdao 266520 (China)

    2016-02-01

    Developing a more accurate greenhouse gas (GHG) emissions inventory draws too much attention. Because of its resource endowment and technical status, China has made coal-related GHG emissions a big part of its inventory. Lacking a stoichiometric carbon conversion coefficient and influenced by geological conditions and mining technologies, previous efforts to estimate fugitive methane emissions from coal mining in China has led to disagreeing results. This paper proposes a new calculation methodology to determine fugitive methane emissions from coal mining based on the domestic analysis of gas geology, gas emission features, and the merits and demerits of existing estimation methods. This new approach involves four main parameters: in-situ original gas content, gas remaining post-desorption, raw coal production, and mining influence coefficient. The case studies in Huaibei–Huainan Coalfield and Jincheng Coalfield show that the new method obtains the smallest error, + 9.59% and 7.01% respectively compared with other methods, Tier 1 and Tier 2 (with two samples) in this study, which resulted in + 140.34%, + 138.90%, and − 18.67%, in Huaibei–Huainan Coalfield, while + 64.36%, + 47.07%, and − 14.91% in Jincheng Coalfield. Compared with the predominantly used methods, this new one possesses the characteristics of not only being a comparably more simple process and lower uncertainty than the “emission factor method” (IPCC recommended Tier 1 and Tier 2), but also having easier data accessibility, similar uncertainty, and additional post-mining emissions compared to the “absolute gas emission method” (IPCC recommended Tier 3). Therefore, methane emissions dissipated from most of the producing coal mines worldwide could be more accurately and more easily estimated. - Highlights: • Propose a new method to estimate fugitive methane emissions from coal mining. • New method has accurate prediction for CMM emissions without activity data updating. • Mining

  19. Dust collector

    Energy Technology Data Exchange (ETDEWEB)

    Sahourin, H.

    1988-03-22

    This invention relates to a dust collector or filter which may be used for large volume cleaning air for gases or for separating out industrial byproducts such as wood chips, sawdust, and shavings. It relies on filtration or separation using only a uniquely configured medium. A primary, but not exclusive, purpose of the invention is to enable very large throughput, capable of separating or filtering of gases containing up to three or more tons of byproduct with a minimum pressure-drop across the device. No preliminary cycloning, to remove major particulates is necessary. The collector generally comprises a continuous and integral filter medium which is suspended from a plurality of downwardly extending frames forming a series of separate elements having a triangular cross-section, each element being relatively wide at the top and narrow at the bottom to define, between adjacent elements, a divergent collecting space which is wide at the bottom. 11 figs.

  20. Dust Measurements in Tokamaks

    International Nuclear Information System (INIS)

    Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M

    2008-01-01

    Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 (micro)m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics

  1. Fugitive emissions control on dry copper tailing with crushed rock armor

    International Nuclear Information System (INIS)

    Haase, E.F.

    1992-01-01

    Four inactive copper tailing impoundments totalling 1,900 acres near Ajo in southwestern Arizona were covered on horizontal surfaces with a 2 in. nominal thickness of crushed rock to control particulate emissions. The tailings are typically dominated by sand-sized particles but may also include significant PM 10 fractions towards the centers of the impoundments. The technology was selected by Phelps Dodge Corporation, after investigation of several alternatives, as a permanent and practical cover that essentially eliminates fugitive emissions. It simulates the natural desert pavement that characterizes this arid area of the Sonoran Desert. Rocky overburden was crushed to minus 3 in. diameter and broadcast on dry surfaces of tailing impoundments with all-terrain, balloon-tired spreaders. Stony residues in the rock armor tend to cement together following rainfall, forming a crust that enhances surface stability and erosion control. Slopes with windblown tailing deposition were covered to a nominal 6 in. thickness by conventional dozer pushing and blading of minus 10 in. rock over the sides. Athel trees, planted extensively since 1970 on two of the four inactive impoundments, provided partial control of fugitives, but were subjected to harsh environmental conditions, including abrasion from saltating particles. The rock armor functions as a mulch which is expected to improve water relations for existing vegetation and areas seeded with native species. New surface microenvironments, and the virtual elimination of surface creep and saltation, are expected to support native plant growth under favorable climatic conditions

  2. Natural gas fugitive emissions rates constrained by global atmospheric methane and ethane.

    Science.gov (United States)

    Schwietzke, Stefan; Griffin, W Michael; Matthews, H Scott; Bruhwiler, Lori M P

    2014-07-15

    The amount of methane emissions released by the natural gas (NG) industry is a critical and uncertain value for various industry and policy decisions, such as for determining the climate implications of using NG over coal. Previous studies have estimated fugitive emissions rates (FER)--the fraction of produced NG (mainly methane and ethane) escaped to the atmosphere--between 1 and 9%. Most of these studies rely on few and outdated measurements, and some may represent only temporal/regional NG industry snapshots. This study estimates NG industry representative FER using global atmospheric methane and ethane measurements over three decades, and literature ranges of (i) tracer gas atmospheric lifetimes, (ii) non-NG source estimates, and (iii) fossil fuel fugitive gas hydrocarbon compositions. The modeling suggests an upper bound global average FER of 5% during 2006-2011, and a most likely FER of 2-4% since 2000, trending downward. These results do not account for highly uncertain natural hydrocarbon seepage, which could lower the FER. Further emissions reductions by the NG industry may be needed to ensure climate benefits over coal during the next few decades.

  3. A Mobile Sensing Approach for Regional Surveillance of Fugitive Methane Emissions in Oil and Gas Production.

    Science.gov (United States)

    Albertson, John D; Harvey, Tierney; Foderaro, Greg; Zhu, Pingping; Zhou, Xiaochi; Ferrari, Silvia; Amin, M Shahrooz; Modrak, Mark; Brantley, Halley; Thoma, Eben D

    2016-03-01

    This paper addresses the need for surveillance of fugitive methane emissions over broad geographical regions. Most existing techniques suffer from being either extensive (but qualitative) or quantitative (but intensive with poor scalability). A total of two novel advancements are made here. First, a recursive Bayesian method is presented for probabilistically characterizing fugitive point-sources from mobile sensor data. This approach is made possible by a new cross-plume integrated dispersion formulation that overcomes much of the need for time-averaging concentration data. The method is tested here against a limited data set of controlled methane release and shown to perform well. We then present an information-theoretic approach to plan the paths of the sensor-equipped vehicle, where the path is chosen so as to maximize expected reduction in integrated target source rate uncertainty in the region, subject to given starting and ending positions and prevailing meteorological conditions. The information-driven sensor path planning algorithm is tested and shown to provide robust results across a wide range of conditions. An overall system concept is presented for optionally piggybacking of these techniques onto normal industry maintenance operations using sensor-equipped work trucks.

  4. Fugitive emission rates assessment of PM2.5 and PM10 from open storage piles in China

    Science.gov (United States)

    Cao, Yiqi; Liu, Tao; He, Jiao

    2018-03-01

    An assessment of the fugitive emission rates of PM2.5 and PM10 from an open static coal and mine storage piles. The experiment was conducted at a large union steel enterprises in the East China region to effectively control the fugitive particulate emissions pollution on daily work and extreme weather conditions. Wind tunnel experiments conducted on the surface of static storage piles, and it generated specific fugitive emission rates (SERs) at ground level of between ca.10-1 and ca.102 (mg/m2·s) for PM2.5 and between ca.101 and ca.103 (mg/m2·s) for PM10 under the u*(wind velocity) between ca.3.0 (m/s) and 10.0 (m/s). Research results show that SERs of different materials differ a lot. Material particulate that has lower surface moisture content generate higher SER and coal material generate higher SER than mine material. For material storage piles with good water infiltrating properties, aspersion is a very effective measure for control fugitive particulate emission.

  5. Performance Evaluations and Quality Validation System for Optical Gas Imaging Cameras That Visualize Fugitive Hydrocarbon Gas Emissions

    Science.gov (United States)

    Optical gas imaging (OGI) cameras have the unique ability to exploit the electromagnetic properties of fugitive chemical vapors to make invisible gases visible. This ability is extremely useful for industrial facilities trying to mitigate product losses from escaping gas and fac...

  6. CHARACTERIZATION OF FUGITIVE MERCURY EMISSIONS FROM THE CELL BUILDING AT A U.S. CHLOR-ALKALI PLANT

    Science.gov (United States)

    The paper discusses an extensive measurement campaign that was conducted of the fugitive (non-ducted) airborne elemental mercury [Hg(0)] emissions from the cell building of a chlor-alkali plant (CAP) located in the southeastern United States. The objectives of this study were to ...

  7. Quantifying Fugitive Methane Emissions from Natural Gas Production with Mobile Technology

    Science.gov (United States)

    Tsai, T.; Rella, C.; Crosson, E.

    2013-12-01

    Quantification of fugitive methane (CH4) emissions to determine the environmental impact of natural gas production is challenging with current methods. We present a new mobile method known as the Plume Scanner that can quickly quantify CH4 emissions of point sources. The Plume Scanner is a direct measurement technique which utilizes a mobile Picarro cavity ring-down spectrometer and a gas sampling system based on AirCore technology [1]. As the Plume Scanner vehicle drives through the plume, the air is simultaneously sampled at four different heights, and therefore, the spatial CH4 distribution can be captured (Fig. 1). The flux of the plume is then determined by multiplying the spatial CH4 distribution data with the anemometer measurements. In this way, fugitive emission rates of highly localized sources such as natural gas production pads can be made quickly (~7 min). Verification with controlled CH4 releases demonstrate that under stable atmospheric conditions (Pasquill stability class is C or greater), the Plume Scanner measurements have an error of 2% and a repeatability of 15% [2]. Under unstable atmospheric conditions (Class A or B), the error is 6%, and the repeatability increases to 70% due to the variability of wind conditions. Over two weeks, 275 facilities in the Barnett Shale were surveyed from public roads by sampling the air for elevations in CH4 concentration, and 77% were found leaking. Emissions from 52 sites have been quantified with the Plume Scanner (Fig. 2), and the total emission is 4,900 liters per min (lpm) or 39,000 metric tons/yr CO2e. 1. Karion, A., C. Sweeney, P. Tans, and T. Newberger (2010), AirCore: An innovative atmospheric sampling system, J. Atmos. Oceanic Tech, 27, 1839-1853. 2. F. Pasquill (1961), The estimation of the dispersion of wind borne material, Meterol. Mag., 90(1063), 33-49 Figure 1. Plume Scanner Cartoon Figure 2. Distribution of methane fugitive emissions with error bars associated with the Pasquill stability classes

  8. Past, present and future of dust research at the Elliot Lake Laboratory

    International Nuclear Information System (INIS)

    Grenier, M.; Bigu, J.

    1985-12-01

    A brief history of the dust research work at the Elliot Lake Laboratory is given. Two decades of dust research work are studied and reviewed. This review clearly shows where, when, and with what intensity various components of dust research were performed. From the data presented here, it is suggested that a major portion of the future efforts be aimed at research directed towards the control and suppression of dust in underground mines

  9. Methane fugitive emissions quantification using the novel 'plume camera' (spatial correlation) method

    Science.gov (United States)

    Crosson, E.; Rella, C.

    2012-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Given that the global warming potential of methane is many times greater than that of carbon dioxide, the importance of quantifying methane emissions becomes clear. The rapidly increasing reliance on shale gas (or other unconventional sources) is only intensifying the interest in fugitive methane releases. Natural gas (which is predominantly methane) is an attractive energy source, as it emits 40% less carbon dioxide per Joule of energy generated than coal. However, if just a small percentage of the natural gas consumed is lost due to fugitive emissions during production, processing, or transport, this global warming benefit is lost (Howarth et al. 2012). It is therefore imperative, as production of natural gas increases, that the fugitive emissions of methane are quantified accurately. Traditional direct measurement techniques often involve physical access of the leak itself to quantify the emissions rate, and are generally require painstaking effort to first find the leak and then quantify the emissions rate. With over half a million natural gas producing wells in the U.S. (U.S. Energy Information Administration), not including the associated processing, storage, and transport facilities, and with each facility having hundreds or even thousands of fittings that can potentially leak, the need is clear to develop methodologies that can provide a rapid and accurate assessment of the total emissions rate on a per-well head basis. In this paper we present a novel method for emissions quantification which uses a 'plume camera' with three 'pixels' to quantify emissions using direct measurements of methane concentration in the downwind plume. By analyzing the spatial correlation between the pixels, the spatial extent of the instantaneous plume can be inferred. This information, when combined with the wind speed through the measurement plane, provides a direct

  10. Measurements of industrial fugitive emissions by the FTIR Tracer Method (FTM)

    International Nuclear Information System (INIS)

    Mellqvist, J.; Arlander, B.; Galle, B.; Bergqvist, B.

    1996-01-01

    A new method called the FTIR Tracer Method (FTM), has been developed for measuring and quantifying fugitive (diffuse) emissions of hydrocarbons. The method has been evaluated in field experiments which were conducted in the vicinity of several petrochemical plants and an oil refinery during 1993-1995. The technique is based on concentration measurements with infrared remote sensing by Long Path Fourier Transform InfraRed (LPFTIR), combined with tracer releases. The field experiments show the FTM to be very useful for mass flux measurements of both alkanes and alkenes and that the measurements are consistent with the conventional SF 6 method. However, the technique needs to be further validated and a more thorough understanding of the measurement uncertainties have to be achieved

  11. Investigation of Natural Gas Fugitive Leak Detection Using an Unmanned Aerial Vehicle

    Science.gov (United States)

    Yang, S.; Talbot, R. W.; Frish, M. B.; Golston, L.; Aubut, N. F.; Zondlo, M. A.

    2017-12-01

    The U.S is now the world's largest natural gas producer, of which methane (CH4) is the main component. About 2% of the CH4 is lost through fugitive leaks. This research is under the DOE Methane Observation Networks with Innovative Technology to Obtain Reductions (MONITOR) program of ARPA-E. Our sentry measurement system is composed of four state-of-the-art technologies centered around the RMLDTM (Remote Methane Leak Detector). An open path RMLDTM measures column-integrated CH4 concentration that incorporates fluctuations in the vertical CH4 distribution. Based on Backscatter Tunable Diode Laser Absorption Spectroscopy and Small Unmanned Aerial Vehicles, the sentry system can autonomously, consistently and cost-effectively monitor and quantify CH4 leakage from sites associated with natural gas production. This system provides an advanced capability in detecting leaks at hard-to-access sites (e.g., wellheads) compared to traditional manual methods. Automated leak detecting and reporting algorithms combined with wireless data link implement real-time leak information reporting. Early data were gathered to set up and test the prototype system, and to optimize the leak localization and calculation strategies. The flight pattern is based on a raster scan which can generate interpolated CH4 concentration maps. The localization and quantification algorithms can be derived from the plume images combined with wind vectors. Currently, the accuracy of localization algorithm can reach 2 m and the calculation algorithm has a factor of 2 accuracy. This study places particular emphasis on flux quantification. The data collected at Colorado and Houston test fields were processed, and the correlation between flux and other parameters analyzed. Higher wind speeds and lower wind variation are preferred to optimize flux estimation. Eventually, this system will supply an enhanced detection capability to significantly reduce fugitive CH4 emissions in the natural gas industry.

  12. Environmental impact of atmospheric fugitive emissions from amine based post combustion CO{sub 2} capture

    Energy Technology Data Exchange (ETDEWEB)

    Attalla, M.I.; Azzi, M.; Jackson, P.; Angove, D. [CSIRO, Newcastle, NSW (Australia). Energy Technology Div

    2009-07-01

    Amine solvent-based chemical absorption of CO{sub 2} is the most mature technology for post combustion capture (PCC) and will likely to be the first to reach commercial scale application. As such, potentially millions of tonnes of solvent will be used per year. In order to ensure the viability of PCC, the potential environmental impacts of fugitive emissions on terrestrial, aquatic and atmospheric environments must be investigated. This study used controlled laboratory/ pilot scale experiments to determine the major chemical components emitted under different operating conditions. As well, the atmospheric photo-oxidation products of amines were studied in a smog chamber under ambient conditions. The environmental concerns associated with these emissions include entrainment of the amine/ammonia with the treated flue gas and their associated atmospheric chemical reaction pathways; formation of ammonia and other amine degradation products can be entrained with the flue gas to the atmosphere; nitrosamines may form as a result of the reaction between an amine and nitrogen oxide; and the mounting evidence of the presence of amines in particulate phase. The chemical compositions of potential fugitive emissions in the flue gases from the CO{sub 2} capture system were estimated. The CSIRO smog chamber was then used to assess the potential environmental impact of selected relevant compounds in terms of their reactivities to produce secondary products. These secondary products were then characterized to determine their potential health risk factors. An air quality model was used to evaluate the potential impact of using amine solutions for CO{sub 2} capture and to determine the trade-off between CO{sub 2} capture and local and regional air quality.

  13. LADEE LUNAR DUST EXPERIMENT

    Data.gov (United States)

    National Aeronautics and Space Administration — This archive bundle includes data taken by the Lunar Dust Experiment (LDEX) instrument aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft....

  14. Construction dust amelioration techniques.

    Science.gov (United States)

    2012-04-01

    Dust produced on seasonal road construction sites in Alaska is both a traffic safety and environmental concern. Dust emanating from : unpaved road surfaces during construction severely reduces visibility and impacts stopping sight distance, and contr...

  15. On Dust Charging Equation

    OpenAIRE

    Tsintsadze, Nodar L.; Tsintsadze, Levan N.

    2008-01-01

    A general derivation of the charging equation of a dust grain is presented, and indicated where and when it can be used. A problem of linear fluctuations of charges on the surface of the dust grain is discussed.

  16. Physics of interstellar dust

    CERN Document Server

    Krugel, Endrik

    2002-01-01

    The dielectric permeability; How to evaluate grain cross sections; Very small and very big particles; Case studies of Mie calculus; Particle statistics; The radiative transition probability; Structure and composition of dust; Dust radiation; Dust and its environment; Polarization; Grain alignment; PAHs and spectral features of dust; Radiative transport; Diffuse matter in the Milky Way; Stars and their formation; Emission from young stars. Appendices Mathematical formulae; List of symbols.

  17. Dust as a surfactant

    International Nuclear Information System (INIS)

    Ignatov, A M; Schram, P P J M; Trigger, S A

    2003-01-01

    We argue that dust immersed in a plasma sheath acts as a surfactant. By considering the momentum balance in a plasma sheath, we evaluate the dependence of the plasma surface pressure on the dust density. It is shown that the dust may reduce the surface pressure, giving rise to a sufficiently strong tangential force. The latter is capable of confining the dust layer inside the sheath in the direction perpendicular to the ion flow

  18. Suppressed Belief

    Directory of Open Access Journals (Sweden)

    Komarine Romdenh-Romluc

    2009-12-01

    Full Text Available Moran’s revised conception of conscious belief requires us to reconceptualise suppressed belief. The work of Merleau-Ponty offers a way to do this. His account of motor-skills allows us to understand suppressed beliefs as pre-reflective ways of dealing with the world.

  19. Road dust and its effect on human health: a literature review

    Science.gov (United States)

    2018-01-01

    The purpose of this study was to determine the effects of road dust on human health. A PubMed search was used to extract references that included the words “road dust” and “health” or “fugitive dust” and “health” in the title or abstract. A total of 46 references were extracted and selected for review after the primary screening of 949 articles. The respiratory system was found to be the most affected system in the human body. Lead, platinum-group elements (platinum, rhodium, and bohrium), aluminum, zinc, vanadium, and polycyclic aromatic hydrocarbons were the components of road dust that were most frequently referenced in the articles reviewed. Road dust was found to have harmful effects on the human body, especially on the respiratory system. To determine the complex mechanism of action of various components of road dust on the human body and the results thereof, the authors recommend a further meta-analysis and extensive risk-assessment research into the health impacts of dust exposure. PMID:29642653

  20. Connecting the Plots: The Extension of Return and Korean Ethnic Nationalism in Jane Jeong Trenka’s 'Fugitive Visions'

    Directory of Open Access Journals (Sweden)

    Ethan Waddell

    2017-05-01

    Full Text Available Thousands of overseas Korean adoptees return to Korea temporarily each year in search of their true origin, but few choose to stay permanently. A prominent member of this small community is Jane Jeong Trenka, author of two memoirs: The Language of Blood (2003 and Fugitive Visions: An Adoptee’s Return to Korea (2009. This article analyses Trenka’s literary struggle for permanence in Fugitive Visions through theories on Korean ethnic national identity. Using Marshall McLuhan’s idea of media as the ‘extension of man’, it explores the symbiotic relationship between literary media and identity, connecting colonial-era writings on Korean ethnic nationalism to Trenka’s portrayal of transnational return.

  1. Impact of fugitive sources and meteorological parameters on vertical distribution of particulate matter over the industrial agglomeration.

    Science.gov (United States)

    Štrbová, Kristína; Raclavská, Helena; Bílek, Jiří

    2017-12-01

    The aim of the study was to characterize vertical distribution of particulate matter, in an area well known by highest air pollution levels in Europe. A balloon filled with helium with measuring instrumentation was used for vertical observation of air pollution over the fugitive sources in Moravian-Silesian metropolitan area during spring and summer. Synchronously, selected meteorological parameters were recorded together with particulate matter for exploration its relationship with particulate matter. Concentrations of particulate matter in the vertical profile were significantly higher in the spring than in the summer. Significant effect of fugitive sources was observed up to the altitude ∼255 m (∼45 m above ground) in both seasons. The presence of inversion layer was observed at the altitude ∼350 m (120-135 m above ground) at locations with major source traffic load. Both particulate matter concentrations and number of particles for the selected particle sizes decreased with increasing height. Strong correlation of particulate matter with meteorological parameters was not observed. The study represents the first attempt to assess the vertical profile over the fugitive emission sources - old environmental burdens in industrial region. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Fugitive methane emissions from natural, urban, agricultural, and energy-production landscapes of eastern Australia

    Science.gov (United States)

    Kelly, Bryce F. J.; Iverach, Charlotte P.; Lowry, Dave; Fisher, Rebecca E.; France, James L.; Nisbet, Euan G.

    2015-04-01

    Modern cavity ringdown spectroscopy systems (CRDS) enable the continuous measurement of methane concentration. This allows for improved quantification of greenhouse gas emissions associated with various natural and human landscapes. We present a subset of over 4000 km of continuous methane surveying along the east coast of Australia, made using a Picarro G2301 CRDS, deployed in a utility vehicle with an air inlet above the roof at 2.2 mAGL. Measurements were made every 5 seconds to a precision of cut coal mines, unconventional gas developments (coal seam gas; CSG), and leaks detected in cities and country towns. In areas of dryland crops the median methane concentration was 1.78 ppm, while in the irrigation districts located on vertisol soils the concentration was as low as 1.76 ppm, which may indicate that these soils are a sink for methane. In the Hunter Valley, New South Wales, open-cut coal mining district we mapped a continuous 50 km interval where the concentration of methane exceeded 1.80 ppm. The median concentration in this interval was 2.02 ppm. Peak readings were beyond the range of the reliable measurement (in excess of 3.00 ppm). This extended plume is an amalgamation of plumes from 17 major pits 1 to 10 km in length. Adjacent to CSG developments in the Surat Basin, southeast Queensland, only small anomalies were detected near the well-heads. Throughout the vast majority of the gas fields the concentration of methane was below 1.80 ppm. The largest source of fugitive methane associated with CSG was off-gassing methane from the co-produced water holding ponds. At one location the down wind plume had a cross section of approximately 1 km where the concentration of methane was above 1.80 ppm. The median concentration within this section was 1.82 ppm, with a peak reading of 2.11 ppm. The ambient air methane concentration was always higher in urban environments compared to the surrounding countryside. Along one major road in Sydney we mapped an interval

  3. Quantification of Fugitive Methane Emissions with Spatially Correlated Measurements Collected with Novel Plume Camera

    Science.gov (United States)

    Tsai, Tracy; Rella, Chris; Crosson, Eric

    2013-04-01

    Quantification of fugitive methane emissions from unconventional natural gas (i.e. shale gas, tight sand gas, etc.) production, processing, and transport is essential for scientists, policy-makers, and the energy industry, because methane has a global warming potential of at least 21 times that of carbon dioxide over a span of 100 years [1]. Therefore, fugitive emissions reduce any environmental benefits to using natural gas instead of traditional fossil fuels [2]. Current measurement techniques involve first locating all the possible leaks and then measuring the emission of each leak. This technique is a painstaking and slow process that cannot be scaled up to the large size of the natural gas industry in which there are at least half a million natural gas wells in the United States alone [3]. An alternative method is to calculate the emission of a plume through dispersion modeling. This method is a scalable approach since all the individual leaks within a natural gas facility can be aggregated into a single plume measurement. However, plume dispersion modeling requires additional knowledge of the distance to the source, atmospheric turbulence, and local topography, and it is a mathematically intensive process. Therefore, there is a need for an instrument capable of simple, rapid, and accurate measurements of fugitive methane emissions on a per well head scale. We will present the "plume camera" instrument, which simultaneously measures methane at different spatial points or pixels. The spatial correlation between methane measurements provides spatial information of the plume, and in addition to the wind measurement collected with a sonic anemometer, the flux can be determined. Unlike the plume dispersion model, this approach does not require knowledge of the distance to the source and atmospheric conditions. Moreover, the instrument can fit inside a standard car such that emission measurements can be performed on a per well head basis. In a controlled experiment

  4. Battling coal and rock dust in mines. Bor'ba s ugol'noi i porodnoi pyl'yu v shakhtakh

    Energy Technology Data Exchange (ETDEWEB)

    Petrukhin, P.M.; Grodel, G.S.; Korenev, A.P.; Krivokhizha, B.M.; Kul' bachnyi, A.N.; Lyubimova, A.I.; Medvedev, E.N.; Yaremachenko, P.P.; Zhilyaev, N.I.

    1981-01-01

    The problems of comprehensive removal of dust from the atmosphere in mines are discussed. Physical and pnysicochemical properties of mine dust are described, which are important for estimating the processes of its formation, spread, and suppression. Presented are the results of theoretical and natural studies of dust aerodynamics of mines. Modern methods for battling coal and rock dust in mines, as well as means of monitoring the dust level of the air are outlined. Technical descriptions are given for new instruments for changing the dust level of the air. Brief reports are given on the preliminary wetting of coal in the massif, and theoretical and practical problems are discussed concerning hydrological methods of dust removal, dust suppression by foam, and dust trapping during the operation of mining equipment, and also on removal of dust from the air at the surface complex of a mine.

  5. Utilization of ultrasonic atomization for dust control in underground mining

    Science.gov (United States)

    Okawa, Hirokazu; Nishi, Kentaro; Kawamura, Youhei; Kato, Takahiro; Sugawara, Katsuyasu

    2017-07-01

    This study examined dust suppression using water particles generated by ultrasonic atomization (2.4 MHz) at low temperature (10 °C). Green tuff (4 µm), green tuff (6 µm), kaolin, and silica were used as dust samples. Even though ultrasonic atomization makes fine water particles, raising relative air humidity immediately was difficult at low temperature. However, remaining water particles that did not change to water vapor contributed to suppression of dust dispersion. Additionally, the effect of water vapor amount (absolute humidity) and water particles generated by ultrasonic atomization on the amount of dust dispersion was investigated using experimental data at temperatures of 10, 20, and 30 °C. Utilization of ultrasound atomization at low temperature has the advantages of low humidity increments in the working space and water particles remaining stable even with low relative air humidity.

  6. Is Optical Gas Imaging Effective for Detecting Fugitive Methane Emissions? - A Technological and Policy Perspective

    Science.gov (United States)

    Ravikumar, A. P.; Wang, J.; Brandt, A. R.

    2016-12-01

    Mitigating fugitive methane emissions from the oil and gas industry has become an important concern for both businesses and regulators. While recent studies have improved our understanding of emissions from all sectors of the natural gas supply chain, cost-effectively identifying leaks over expansive natural gas infrastructure remains a significant challenge. Recently, the Environmental Protection Agency (EPA) has recommended the use of optical gas imaging (OGI) technologies to be used in industry-wide leak detection and repair (LDAR) programs. However, there has been little to no systematic study of the effectiveness of infrared-camera-based OGI technology for leak detection applications. Here, we develop a physics-based model that simulates a passive infrared camera imaging a methane leak against varying background and ambient conditions. We verify the simulation tool through a series of large-volume controlled release field experiments wherein known quantities of methane were released and imaged from a range of distances. After simulator verification, we analyze the effects of environmental conditions like temperature, wind, and imaging background on the amount of methane detected from a statistically representative survey program. We also examine the effects of LDAR design parameters like imaging distance, leak size distribution, and gas composition. We show that imaging distance strongly affects leak detection - EPA's expectation of a 60% reduction in fugitive emissions based on a semi-annual LDAR survey will be realized only if leaks are imaged at a distance less than 10 m from the source under ideal environmental conditions. Local wind speed is also shown to be important. We show that minimum detection limits are 3 to 4 times higher for wet-gas compositions that contain a significant fraction of ethane and propane, resulting a significantly large leakage rate. We also explore the importance of `super-emitters' on the performance of an OGI-based leak

  7. The Lunar Dust Environment

    Science.gov (United States)

    Szalay, Jamey Robert

    Planetary bodies throughout the solar system are continually bombarded by dust particles, largely originating from cometary activities and asteroidal collisions. Surfaces of bodies with thick atmospheres, such as Venus, Earth, Mars and Titan are mostly protected from incoming dust impacts as these particles ablate in their atmospheres as 'shooting stars'. However, the majority of bodies in the solar system have no appreciable atmosphere and their surfaces are directly exposed to the flux of high speed dust grains. Impacts onto solid surfaces in space generate charged and neutral gas clouds, as well as solid secondary ejecta dust particles. Gravitationally bound ejecta clouds forming dust exospheres were recognized by in situ dust instruments around the icy moons of Jupiter and Saturn, and had not yet been observed near bodies with refractory regolith surfaces before NASA's Lunar Dust and Environment Explorer (LADEE) mission. In this thesis, we first present the measurements taken by the Lunar Dust Explorer (LDEX), aboard LADEE, which discovered a permanently present, asymmetric dust cloud surrounding the Moon. The global characteristics of the lunar dust cloud are discussed as a function of a variety of variables such as altitude, solar longitude, local time, and lunar phase. These results are compared with models for lunar dust cloud generation. Second, we present an analysis of the groupings of impacts measured by LDEX, which represent detections of dense ejecta plumes above the lunar surface. These measurements are put in the context of understanding the response of the lunar surface to meteoroid bombardment and how to use other airless bodies in the solar system as detectors for their local meteoroid environment. Third, we present the first in-situ dust measurements taken over the lunar sunrise terminator. Having found no excess of small grains in this region, we discuss its implications for the putative population of electrostatically lofted dust.

  8. Influence of Air Humidity and Water Particles on Dust Control Using Ultrasonic Atomization

    Science.gov (United States)

    Okawa, Hirokazu; Nishi, Kentaro; Shindo, Dai; Kawamura, Youhei

    2012-07-01

    The influence of air humidity and water particles on dust control was examined using ultrasonic atomization at 2.4 MHz, an acrylic box (61 L), and four types of ore dust samples: green tuff (4 µm), green tuff (6 µm), kaolin, and silica. It was clearly demonstrated that ultrasonic atomization was effective in raising humidity rapidly. However, at high relative air humidity, the water particles remained stable in the box without changing to water vapor. Ultrasonic atomization was applied to suppress dust dispersion and 40-95% dust reduction was achieved at 83% relative air humidity. Dust dispersion was more effective with ultrasonic atomization than without.

  9. Practical Design Guidelines for Fugitive Gas Detection from Unmanned Aerial Vehicles

    Science.gov (United States)

    Tandy, William D., Jr.

    Simulation, design, and analysis are combined in this effort to realize a UAV-scale instrument for fugitive gas detection. The contributing material to the industry begins by extending and correlating an integrated Gaussian plume model useful for instrument predictions and trade studies, regardless of the instrument type or molecule of interest. A variety of generally applicable plots are produced from this foundation, including receiver operator curves for leak rate detectability vs. wind speed, beam diameter vs. leak rate detectability, and plots for required scan densities. The atmospheric and instrument parameter trade studies are followed by hardware-specific analyses applicable to differential absorption lidar (DIAL) instruments. A synopsis of the lessons learned from hands-on experiences in the lab further define the design space for DIAL sensors. The dissertation culminates in the detailed design and analysis of two DIAL instrument concepts. The conclusion is that a DIAL instrument capable of reliably detecting a 50 SCFH plume in winds speeds up to 7 mph is on the threshold of being achievable on a quadcopter platform. Of special note is that the effort was funded by a Pipeline and Hazardous Materials Safety Administration grant and performed in collaboration with Ball Aerospace & Technologies.

  10. Assessment for potential radionuclide emissions from stacks and diffuse and fugitive sources on the Hanford Site

    International Nuclear Information System (INIS)

    Davis, W.E.; Schmidt, J.W.; Gleckler, B.P.; Rhoads, K.

    1995-06-01

    By using the six EPA-approved methods, instead of only the original back calculation method for assessing the 84 WHC registered stacks, the number of stacks requiring continuous monitoring was reduced from 32 to 19 stacks. The intercomparison between results showed that no correlation existed between back calculations and release fractions. Also the NDA, upstream air samples, and powder release fraction method results were at least three orders of magnitude lower then the back calculations results. The most surprising results of the assessment came from NDA. NDA was found to be an easy method for assessing potential emissions. For the nine stacks assessed by NDA, all nine of the stacks would have required continuous monitoring when assessed by back calculations. However, when NDA was applied all stacks had potential emissions that would cause an EDE below the > 0.1 mrem/y standard. Apparent DFs for the HEPA filter systems were calculated for eight nondesignated stacks with emissions above the detection limit. These apparent DFs ranged from 0.5 to 250. The EDE dose to the MEI was calculated to be 0.028 mrem/y for diffuse and fugitive emissions from the Hanford Sited. This is well below the > 0.1 mrem/y standard

  11. Fugitive emission source characterization using a gradient-based optimization scheme and scalar transport adjoint

    Science.gov (United States)

    Brereton, Carol A.; Joynes, Ian M.; Campbell, Lucy J.; Johnson, Matthew R.

    2018-05-01

    Fugitive emissions are important sources of greenhouse gases and lost product in the energy sector that can be difficult to detect, but are often easily mitigated once they are known, located, and quantified. In this paper, a scalar transport adjoint-based optimization method is presented to locate and quantify unknown emission sources from downstream measurements. This emission characterization approach correctly predicted locations to within 5 m and magnitudes to within 13% of experimental release data from Project Prairie Grass. The method was further demonstrated on simulated simultaneous releases in a complex 3-D geometry based on an Alberta gas plant. Reconstructions were performed using both the complex 3-D transient wind field used to generate the simulated release data and using a sequential series of steady-state RANS wind simulations (SSWS) representing 30 s intervals of physical time. Both the detailed transient and the simplified wind field series could be used to correctly locate major sources and predict their emission rates within 10%, while predicting total emission rates from all sources within 24%. This SSWS case would be much easier to implement in a real-world application, and gives rise to the possibility of developing pre-computed databases of both wind and scalar transport adjoints to reduce computational time.

  12. The development of allergic inflammation in a murine house dust mite asthma model is suppressed by synbiotic mixtures of non-digestible oligosaccharides and Bifidobacterium breve M-16V.

    Science.gov (United States)

    Verheijden, K A T; Willemsen, L E M; Braber, S; Leusink-Muis, T; Jeurink, P V; Garssen, J; Kraneveld, A D; Folkerts, G

    2016-04-01

    The incidence and severity of allergic asthma is rising, and novel strategies to prevent or treat this disease are needed. This study investigated the effects of different mixtures of non-digestible oligosaccharides combined with Bifidobacterium breve M-16V (BB) on the development of allergic airway inflammation in an animal model for house dust mite (HDM)-induced allergic asthma. BALB/c mice were sensitized intranasally (i.n.) with HDM and subsequently challenged (i.n.) with PBS or HDM while being fed diets containing different oligosaccharide mixtures in combination with BB or an isocaloric identical control diet. Bronchoalveolar lavage fluid (BALF) inflammatory cell influx, chemokine and cytokine concentrations in lung homogenates and supernatants of ex vivo HDM-restimulated lung cells were analyzed. The HDM-induced influx of eosinophils and lymphocytes was reduced by the diet containing the short-chain and long-chain fructo-oligosaccharides and BB (FFBB). In addition to the HDM-induced cell influx, concentrations of IL-33, CCL17, CCL22, IL-6, IL-13 and IL-5 were increased in supernatants of lung homogenates or BALF and IL-4, IFN-γ and IL-10 were increased in restimulated lung cell suspensions of HDM-allergic mice. The diet containing FFBB reduced IL-6, IFN-γ, IL-4 and IL-10 concentrations, whereas the combination of galacto-oligosaccharides and long-chain fructo-oligosaccharides with BB was less potent in this model. These findings show that synbiotic dietary supplementation can affect respiratory allergic inflammation induced by HDM. The combination of FFBB was most effective in the prevention of HDM-induced airway inflammation in mice.

  13. Simulation of dust voids in complex plasmas

    Science.gov (United States)

    Goedheer, W. J.; Land, V.

    2008-12-01

    In dusty radio-frequency (RF) discharges under micro-gravity conditions often a void is observed, a dust free region in the discharge center. This void is generated by the drag of the positive ions pulled out of the discharge by the electric field. We have developed a hydrodynamic model for dusty RF discharges in argon to study the behaviour of the void and the interaction between the dust and the plasma background. The model is based on a recently developed theory for the ion drag force and the charging of the dust. With this model, we studied the plasma inside the void and obtained an understanding of the way it is sustained by heat generated in the surrounding dust cloud. When this heating mechanism is suppressed by lowering the RF power, the plasma density inside the void decreases, even below the level where the void collapses, as was recently shown in experiments on board the International Space Station. In this paper we present results of simulations of this collapse. At reduced power levels the collapsed central cloud behaves as an electronegative plasma with corresponding low time-averaged electric fields. This enables the creation of relatively homogeneous Yukawa balls, containing more than 100 000 particles. On earth, thermophoresis can be used to balance gravity and obtain similar dust distributions.

  14. Dust Devil Tracks

    Science.gov (United States)

    2002-01-01

    (Released 8 May 2002) The Science This image, centered near 50.0 S and 17.7 W displays dust devil tracks on the surface. Most of the lighter portions of the image likely have a thin veneer of dust settled on the surface. As a dust devil passes over the surface, it acts as a vacuum and picks up the dust, leaving the darker substrate exposed. In this image there is a general trend of many of the tracks running from east to west or west to east, indicating the general wind direction. There is often no general trend present in dust devil tracks seen in other images. The track patterns are quite ephemeral and can completely change or even disappear over the course of a few months. Dust devils are one of the mechanisms that Mars uses to constantly pump dust into the ubiquitously dusty atmosphere. This atmospheric dust is one of the main driving forces of the present Martian climate. The Story Vrrrrooooooooom. Think of a tornado, the cartoon Tasmanian devil, or any number of vacuum commercials that powerfully suck up swirls of dust and dirt. That's pretty much what it's like on the surface of Mars a lot of the time. Whirlpools of wind called

  15. Interocular suppression

    Science.gov (United States)

    Tuna, Ana Rita; Almeida Neves Carrega, Filipa; Nunes, Amélia Fernandes

    2017-08-01

    The objective of this work is to quantify the suppressive imbalance, based on the manipulation of ocular luminance, between a group of subjects with normal binocular vision and a group of subjects with amblyopia. The result reveals that there are statistically significant differences in interocular dominance between two groups, evidencing a greater suppressive imbalance in amblyopic subjects. The technique used, proved to be a simple, easy to apply and economic method, for quantified ocular dominance. It is presented as a technique with the potential to accompany subjects with a marked dominance in one of the eyes that makes fusion difficult.

  16. Whither Cometary Dust?

    Science.gov (United States)

    Lisse, Carey M.

    2010-10-01

    In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

  17. Communication plan for windblown dust.

    Science.gov (United States)

    2015-05-01

    Windblown dust events occur in Arizona, and blowing dust has been considered a contributing factor to serious crashes on the : segment of Interstate 10 (I10) between Phoenix and Tucson, as well as on other Arizona roadways. Arizonas dust events...

  18. Dust in planetary nebulae

    International Nuclear Information System (INIS)

    Mathis, J.S.

    1978-01-01

    The author's review concentrates on theoretical aspects of dust in planetary nebulae (PN). He considers the questions: how much dust is there is PN; what is its composition; what effects does it have on the ionization structure, on the dynamics of the nebula. (Auth.)

  19. Toxicity of lunar dust

    NARCIS (Netherlands)

    Linnarsson, D.; Carpenter, J.; Fubini, B.; Gerde, P.; Loftus, D.; Prisk, K.; Staufer, U.; Tranfield, E.; van Westrenen, W.

    2012-01-01

    The formation, composition and physical properties of lunar dust are incompletely characterised with regard to human health. While the physical and chemical determinants of dust toxicity for materials such as asbestos, quartz, volcanic ashes and urban particulate matter have been the focus of

  20. Combustible dust tests

    Science.gov (United States)

    The sugar dust explosion in Georgia on February 7, 2008 killed 14 workers and injured many others (OSHA, 2009). As a consequence of this explosion, OSHA revised its Combustible Dust National Emphasis (NEP) program. The NEP targets 64 industries with more than 1,000 inspections and has found more tha...

  1. Respirable dust measured downwind during rock dust application.

    Science.gov (United States)

    Harris, M L; Organiscak, J; Klima, S; Perera, I E

    2017-05-01

    The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH's Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners' exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device.

  2. Inventory assessment and determination of properties of dust contamination in the Shelter under-roof space

    International Nuclear Information System (INIS)

    Bogatov, S.A.

    2000-01-01

    Experimental results on study of radionuclide contamination of surfaces under the roof of Shelter have been analyzed. Values of 'loose' and fixed fuel contamination densities and aerodynamic diameters of dust particles capable of resuspension are obtained. Long term efficiency of dust suppression system under the Shelter roof has been estimated. On the base of retrospective analysis of the results, fuel dust inventory on the surfaces under the Shelter roof was evaluated. 14 refs., 5 tab., 3 figs

  3. Lunar Dust Mitigation Screens

    Science.gov (United States)

    Knutson, Shawn; Holloway, Nancy

    With plans for the United States to return to the moon, and establish a sustainable human presence on the lunar surface many issues must be successfully overcome. Lunar dust is one of a number of issues with the potential to create a myriad of problems if not adequately addressed. Samples of dust brought back from Apollo missions show it to be soft, yet sharp and abrasive. The dust consists of a variety of morphologies including spherical, angular blocks, shards, and a number of irregular shapes. One of the main issues with lunar dust is its attraction to stick to anything it comes in contact with (i.e. astronauts, equipment, habitats, etc.). Ionized radiation from the sun strikes the moon's surface and creates an electrostatic charge on the dust. Further, the dust harbors van der Waals forces making it especially difficult to separate once it sticks to a surface. During the Apollo missions, it was discovered that trying to brush the lunar dust from spacesuits was not effective, and rubbing it caused degradation of the suit material. Further, when entering the lunar module after moonwalks, the astronauts noted that the dust was so prolific inside the cabin that they inhaled and ingested it, causing at least one of them, Harrison "Jack" Schmidt, to report irritation of the throat and lungs. It is speculated that the dust could also harm an astronaut's nervous and cardiovascular systems, especially during an extended stay. In addition to health issues, the dust can also cause problems by scouring reflective coatings off of thermal blankets, and roughening surfaces of windows and optics. Further, panels on solar cells and photovoltaics can also be compromised due to dust sticking on the surfaces. Lunar dust has the capacity to penetrate seals, interfere with connectors, as well as mechanisms on digging machines, all of which can lead to problems and failure. To address lunar dust issues, development of electrostatic screens to mitigate dust on sur-faces is currently

  4. Regional and climatic controls on seasonal dust deposition in the southwestern U.S.

    Science.gov (United States)

    Reheis, M.C.; Urban, F.E.

    2011-01-01

    Vertical dust deposition rates (dust flux) are a complex response to the interaction of seasonal precipitation, wind, changes in plant cover and land use, dust source type, and local vs. distant dust emission in the southwestern U.S. Seasonal dust flux in the Mojave-southern Great Basin (MSGB) deserts, measured from 1999 to 2008, is similar in summer-fall and winter-spring, and antecedent precipitation tends to suppress dust flux in winter-spring. In contrast, dust flux in the eastern Colorado Plateau (ECP) region is much larger in summer-fall than in winter-spring, and twice as large as in the MSGB. ECP dust is related to wind speed, and in the winter-spring to antecedent moisture. Higher summer dust flux in the ECP is likely due to gustier winds and runoff during monsoonal storms when temperature is also higher. Source types in the MSGB and land use in the ECP have important effects on seasonal dust flux. In the MSGB, wet playas produce salt-rich dust during wetter seasons, whereas antecedent and current moisture suppress dust emission from alluvial and dry-playa sources during winter-spring. In the ECP under drought conditions, dust flux at a grazed-and-plowed site increased greatly, and also increased at three annualized, previously grazed sites. Dust fluxes remained relatively consistent at ungrazed and currently grazed sites that have maintained perennial vegetation cover. Under predicted scenarios of future climate change, these results suggest that an increase in summer storms may increase dust flux in both areas, but resultant effects will depend on source type, land use, and vegetation cover. ?? 2011.

  5. Dust Generation Resulting from Desiccation of Playa Systems: Studies on Mono and Owens Lakes, California

    Science.gov (United States)

    Gill, Thomas Edward

    1995-01-01

    Playas, evaporites, and aeolian sediments frequently are linked components within the Earth system. Anthropogenic water diversions from terminal lakes form playas that release fugitive dust. These actions, documented worldwide, simulate aeolian processes activated during palaeoclimatic pluvial/interpluvial transitions, and have significant environmental impacts. Pluvial lakes Russell and Owens in North America's Great Basin preceded historic Mono and Owens Lakes, now desiccated by water diversions into dust-generating, evaporite -encrusted playas. Geochemical and hydrologic cycles acting on the Owens (Dry) Lake playa form three distinct crust types each year. Although initial dust production results from deflation of surface efflorescences after the playa dries, most aerosols are created by saltation abrasion of salt/silt/clay crusts at crust/ sand sheet contacts. The warm-season, clastic "cemented" crust is slowest to degrade into dust. If the playa surface is stabilized by an unbroken, non-efflorescent crust, dust formation is discouraged. When Mono Lake's surFace elevation does not exceed 1951 meters (6400 feet), similar processes will also generate dust from its saline lower playa. Six factors--related to wind, topography, groundwater, and sediments--control dust formation at both playas. These factors were combined into a statistical model relating suspended dust concentrations to playa/lake morphometry. The model shows the extent and severity of Mono Lake dust storms expands significantly below the surface level 6376 feet (1943.5 meters). X-ray diffraction analysis of Mono Basin soils, playa sediments, and aerosols demonstrates geochemical cycling of materials through land, air and water during Mono Lake's 1982 low stand. Soils and clastic playa sediments contain silicate minerals and tephra. Saline groundwater deposited calcite, halite, thenardite, gaylussite, burkeite and glauberite onto the lower playa. Aerosols contained silicate minerals (especially

  6. Development of a life-cycle fugitive methane emissions model utilizing device level emissions and activity factors

    Science.gov (United States)

    Englander, J.; Brandt, A. R.

    2017-12-01

    There has been numerous studies in quantifying the scale of fugitive emissions from across the natural gas value chain. These studies have typically focused on either specific types of equipment (such as valves) or on a single part of the life-cycle of natural gas production (such as gathering stations).1,2 However it has been demonstrated that average emissions factors are not sufficient for representing leaks in the natural gas system.3 In this work, we develop a robust estimate of fugitive emissions rates by incorporating all publicly available studies done at the component up to the process level. From these known studies, we create a database of leaks with normalized nomenclature from which leak estimates can be drawn from actual leak observations. From this database, and parameterized by meta-data such as location, scale of study, or placement in the life-cycle, we construct stochastic emissions factors specific for each process unit. This will be an integrated tool as part of the Oil production greenhouse gas estimator (OPGEE) as well as the Fugitive Emissions Abatement Simulation Toolkit (FEAST) models to enhances their treatment of venting and fugitive emissions, and will be flexible to include user provided data and input parameters.4,51. Thoma, ED et al. Assessment of Uinta Basin Oil and Natural Gas Well Pad Pneumatic Controller Emissions. J. Environ. Prot. 2017. 2. Marchese, AJ et al. Methane Emissions from United States Natural Gas Gathering and Processing. ES&T 2015. doi:10.1021/acs.est.5b02275 3. Brandt, AR et al. Methane Leaks from Natural Gas Systems Follow Extreme Distributions. ES&T 2016. doi:10.1021/acs.est.6b04303 4. El-Houjeiri, HM et al. An open-source LCA tool estimating greenhouse gas emissions from crude oil production using field characteristics. ES&T 2013. doi: 10.1021/es304570m 5. Kemp, CE et al. Comparing Natural Gas Leakage Detection Technologies Using an Open-Source `Virtual Gas Field' Simulator. ES&T 2016. doi:10.1021/acs.est.5b

  7. Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport.

    Science.gov (United States)

    Shahan, M R; Seaman, C E; Beck, T W; Colinet, J F; Mischler, S E

    2017-09-01

    Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. If deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8.

  8. Quantifying Anthropogenic Dust Emissions

    Science.gov (United States)

    Webb, Nicholas P.; Pierre, Caroline

    2018-02-01

    Anthropogenic land use and land cover change, including local environmental disturbances, moderate rates of wind-driven soil erosion and dust emission. These human-dust cycle interactions impact ecosystems and agricultural production, air quality, human health, biogeochemical cycles, and climate. While the impacts of land use activities and land management on aeolian processes can be profound, the interactions are often complex and assessments of anthropogenic dust loads at all scales remain highly uncertain. Here, we critically review the drivers of anthropogenic dust emission and current evaluation approaches. We then identify and describe opportunities to: (1) develop new conceptual frameworks and interdisciplinary approaches that draw on ecological state-and-transition models to improve the accuracy and relevance of assessments of anthropogenic dust emissions; (2) improve model fidelity and capacity for change detection to quantify anthropogenic impacts on aeolian processes; and (3) enhance field research and monitoring networks to support dust model applications to evaluate the impacts of disturbance processes on local to global-scale wind erosion and dust emissions.

  9. Advanced receptor modelling for the apportionment of road dust resuspension to atmospheric PM

    Science.gov (United States)

    Amato, F.; Pandolfi, M.; Escrig, A.; Querol, X.; Alastuey, A.; Pey, J.; Perez, N.; Hopke, P. K.

    2009-04-01

    Fugitive emissions from traffic resuspension can often represent an important source of atmospheric particulate matter in urban environments, especially when the scarce precipitations favour the accumulation of road dust. Resuspension of road dust can lead to high exposures to heavy metals, metalloids and mineral matter. Knowing the amount of its contribution to atmospheric PM is a key task for establishing eventual mitigation or preventive measures. Factor analysis techniques are widely used tools for atmospheric aerosol source apportionment, based on the mass conservation principle. Paatero and Tapper (1993) suggested the use of a Weighted Least Squares scheme with the aim of obtaining a minimum variance solution. Additionally they proposed to incorporate the basic physical constraint of non negativity, calling their approach Positive Matrix Factorization (PMF), which can be performed by the program PMF2 released by Paatero (1997). Nevertheless, Positive Matrix Factorization can be either solved with the Multilinear Engine (ME-2), a more flexible program, also developed by Paatero (1999), which can solve any model consisting in sum of products of unknowns. The main difference with PMF2 is that ME-2 does not solve only well-defined tasks, but its actions are defined in a "script file" written in a special-purpose programming language, allowing incorporating additional tasks such as data processing etc. Thus in ME-2 a priori information, e.g. chemical fingerprints can be included as auxiliary terms of the object function to be minimized. This feature of ME-2 make it especially suitable for source apportionment studies where some knowledge (chemical ratios, profiles, mass conservation etc) of involved sources is available. The aim of this study was to quantify the contribution of road dust resuspension in PM10, PM2.5 and PM1 data set from Barcelona (Spain). Given that recently the emission profile of local road dust was characterized (Amato et al., in press

  10. Spirit Feels Dust Gust

    Science.gov (United States)

    2007-01-01

    On sol 1149 (March 28, 2007) of its mission, NASA's Mars Exploration Rover Spirit caught a wind gust with its navigation camera. A series of navigation camera images were strung together to create this movie. The front of the gust is observable because it was strong enough to lift up dust. From assessing the trajectory of this gust, the atmospheric science team concludes that it is possible that it passed over the rover. There was, however, no noticeable increase in power associated with this gust. In the past, dust devils and gusts have wiped the solar panels of dust, making it easier for the solar panels to absorb sunlight.

  11. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies.

    Science.gov (United States)

    Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

    2012-07-01

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10(-7) torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10(-10) torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  12. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Anthony; Horanyi, Mihaly; Kempf, Sascha; Thomas, Evan [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, Colorado 80303 (United States); Collette, Andrew; Drake, Keith; Northway, Paige [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Laboratory for Atmospheric and Space Physics, 1234 Innovation Drive, Boulder, Colorado 80303 (United States); Gruen, Eberhard [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Mocker, Anna [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); IRS, Universitaet Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Munsat, Tobin [Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80303 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Srama, Ralf [MPI fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); IRS, Universitaet Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); and others

    2012-07-15

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Instituet fuer Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10{sup -7} torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10{sup -10} torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  13. Galactic dust and extinction

    International Nuclear Information System (INIS)

    Lyngaa, G.

    1979-01-01

    The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards l=50 0 than towards l=230 0 . On the smaller scale, much of the dust responsible for extinction is situated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars. (Auth.)

  14. Fugitive emission inventory from Brazilian oil and gas industry (2000-2005) and discussion of mitigation measures

    Energy Technology Data Exchange (ETDEWEB)

    Carloni, Flavia A.; D' Avignon, Alexandre; La Rovere, Emilio L. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Centro Clima

    2008-07-01

    The objective of this work is to evaluate current emissions of GHGs within the Brazilian oil and gas industry, specifically the fugitive emissions arising from exploration and production. Besides, projects for mitigating these emissions and opportunities for the national industry are investigated. Results show that N{sub 2}O contributes little to fugitive emissions from the oil and gas industry, principally from gas sector. NMVOC emissions are significant, principally from the oil sector. In relation to CO{sub 2} and CH{sub 4} emissions, the oil sector emits more CO{sub 2} while the gas sector contributes more to CH{sub 4} emissions. In both sectors flaring is the activity that emits most CO{sub 2}. In relation to CH{sub 4} the principal contribution to emissions are from exploration and production onshore, although offshore activities as a whole play a greater part in the national industry. The results make it clear that the use of gas from flaring activity is a great opportunity for emission mitigation projects. From a business point of view, methane emissions could mean lost opportunities in selling natural gas. The Kyoto Protocol mechanisms, as the Clean Development Mechanism and Joint Implementation actions, provide the opportunity to stimulate investments in projects for reducing flaring and venting of associated gas. (author)

  15. Directional passive ambient air monitoring of ammonia for fugitive source attribution; a field trial with wind tunnel characteristics

    Science.gov (United States)

    Solera García, M. A.; Timmis, R. J.; Van Dijk, N.; Whyatt, J. D.; Leith, I. D.; Leeson, S. R.; Braban, C. F.; Sheppard, L. J.; Sutton, M. A.; Tang, Y. S.

    2017-10-01

    Atmospheric ammonia is a precursor for secondary particulate matter formation, which harms human health and contributes to acidification and eutrophication. Under the 2012 Gothenburg Protocol, 2005 emissions must be cut by 6% by 2020. In the UK, 83% of total emissions originate from agricultural practices such as fertilizer use and rearing of livestock, with emissions that are spatially extensive and variable in nature. Such fugitive emissions make resolving and tracking of individual site performance challenging. The Directional Passive Air quality Sampler (DPAS) was trialled at Whim Bog, an experimental site with a wind-controlled artificial release of ammonia, in combination with CEH-developed ammonia samplers. Whilst saturation issues were identified, two DPAS-MANDE (Mini Annular Denuder) systems, when deployed in parallel, displayed an average relative deviation of 15% (2-54%) across all 12 directions, with the directions exposed to the ammonia source showing ∼5% difference. The DPAS-MANDE has shown great potential for directional discrimination and can contribute to the understanding and management of fugitive ammonia sources from intensive agriculture sites.

  16. Impact of mineral dust on nitrate, sulfate, and ozone in transpacific Asian pollution plumes

    Directory of Open Access Journals (Sweden)

    T. D. Fairlie

    2010-04-01

    Full Text Available We use a 3-D global chemical transport model (GEOS-Chem to interpret aircraft observations of nitrate and sulfate partitioning in transpacific dust plumes during the INTEX-B campaign of April–May 2006. The model includes explicit transport of size-resolved mineral dust and its alkalinity, nitrate, and sulfate content. The observations show that particulate nitrate is primarily associated with dust, sulfate is primarily associated with ammonium, and Asian dust remains alkaline across the Pacific. This can be reproduced in the model by using a reactive uptake coefficient for HNO3 on dust (γ(HNO3 ~10−3 much lower than commonly assumed in models and possibly reflecting limitation of uptake by dust dissolution. The model overestimates gas-phase HNO3 by a factor of 2–3, typical of previous model studies; we show that this cannot be corrected by uptake on dust. We find that the fraction of aerosol nitrate on dust in the model increases from ~30% in fresh Asian outflow to 80–90% over the Northeast Pacific, reflecting in part the volatilization of ammonium nitrate and the resulting transfer of nitrate to the dust. Consumption of dust alkalinity by uptake of acid gases in the model is slow relative to the lifetime of dust against deposition, so that dust does not acidify (at least not in the bulk. This limits the potential for dust iron released by acidification to become bio-available upon dust deposition. Observations in INTEX-B show no detectable ozone depletion in Asian dust plumes, consistent with the model. Uptake of HNO3 by dust, suppressing its recycling to NOx, reduces Asian pollution influence on US surface ozone in the model by 10–15% or up to 1 ppb.

  17. Radioisotope dust pollution monitor

    International Nuclear Information System (INIS)

    Szepke, R.; Harasimczuk, J.; Dobrowiecki, J.

    1990-01-01

    Measuring principles and specification of two dust monitors: station-type AMIZ and portable-type PIK-10 for ambient air pollution are presented. The first one, a fully automatic instrument is destined for permanent monitoring of air pollution in preset sampling time from .25 to 24 hours. The second one was developed as a portable working model. Both instruments display their results in digital form in dust concentration units. (author)

  18. Coal dust symposium

    Energy Technology Data Exchange (ETDEWEB)

    1981-03-01

    This paper gives a report of the paper presented at the symposium held in Hanover on 9 and 10 February 1981. The topics include: the behaviour of dust and coal dust on combustion and explosion; a report on the accidents which occurred at the Laegerdorf cement works' coal crushing and drying plant; current safety requirements at coal crushing and drying plant; and coal crushing and drying. Four papers are individually abstracted. (In German)

  19. Dust devil generation

    International Nuclear Information System (INIS)

    G Onishchenko, O; A Pokhotelov, O; Horton, W; Stenflo, L

    2014-01-01

    The equations describing axi-symmetric nonlinear internal gravity waves in an unstable atmosphere are derived. A hydrodynamic model of a dust devil generation mechanism in such an atmosphere is investigated. It is shown that in an unstably stratified atmosphere the convective plumes with poloidal motion can grow exponentially. Furthermore, it is demonstrated that these convective plumes in an atmosphere with weak large scale toroidal motion are unstable with respect to three-dimensional dust devil generation. (papers)

  20. Remote sensing investigations of fugitive soil arsenic and its effects on vegetation reflectance

    Science.gov (United States)

    Slonecker, E. Terrence

    2007-12-01

    Three different remote sensing technologies were evaluated in support of the remediation of fugitive arsenic and other hazardous waste-related risks to human and ecological health at the Spring Valley Formerly Used Defense Site in northwest Washington D.C., an area of widespread soil arsenic contamination as a result of World War I research and development of chemical weapons. The first evaluation involved the value of information derived from the interpretation of historical aerial photographs. Historical aerial photographs dating back as far as 1918 provided a wealth of information about chemical weapons testing, storage, handling and disposal of these hazardous materials. When analyzed by a trained photo-analyst, the 1918 aerial photographs resulted in 42 features of potential interest. When compared with current remedial activities and known areas of contamination, 33 of 42 or 78.5 % of the features were spatially correlated with current areas of contamination or remedial activity. The second investigation involved the phytoremediation of arsenic through the use of Pteris ferns and the evaluation of the spectral properties of these ferns. Three hundred ferns were grown in controlled laboratory conditions in soils amended with five levels (0, 20, 50, 100 and 200 parts per million) of sodium arsenate. After 20 weeks, the Pteris ferns were shown to have an average uptake concentration of over 4,000 parts per million each. Additionally, statistical analysis of the spectral signature from each fern showed that the frond arsenic concentration could be reasonably predicted with a linear model when the concentration was equal or greater than 500 parts per million. Third, hyperspectral imagery of Spring Valley was obtained and analyzed with a suite of spectral analysis software tools. Results showed the grasses growing in areas of known high soil arsenic could be identified and mapped at an approximate 85% level of accuracy when the hyperspectral image was processed

  1. Quantifying dust plume formation and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    KAUST Repository

    Khan, Basit Ali

    2015-01-01

    Dust particles mixed in the free troposphere have longer lifetimes than airborne particles near the surface. Their cumulative radiative impact on earth’s meteorological processes and climate might be significant despite their relatively small contribution to total dust abundance. One example is the elevated dust--laden Saharan Air Layer (SAL) over the equatorial North Atlantic, which cools the sea surface and likely suppresses hurricane activity. To understand the formation mechanisms of SAL, we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM--I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF--Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground--based observations show that WRF--Chem reproduces observed meteorological fields as well as aerosol distribution across the entire region and along the airplane’s tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface--detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground--based observations are generally good, but suggest

  2. Multiregional environmental comparison of fossil fuel power generation-Assessment of the contribution of fugitive emissions from conventional and unconventional fossil resources

    NARCIS (Netherlands)

    Bouman, Evert A.; Ramirez, Andrea; Hertwich, Edgar G.

    2015-01-01

    In this paper we investigate the influence of fugitive methane emissions from coal, natural gas, and shale gas extraction on the greenhouse gas (GHG) impacts of fossil fuel power generation through its life cycle. A multiregional hybridized life cycle assessment (LCA) model is used to evaluate

  3. Effects of Adding Corn Dried Distiller Grains with Solubles (DDGS to the Dairy Cow Diet and Effects of Bedding in Dairy Cow Slurry on Fugitive Methane Emissions

    Directory of Open Access Journals (Sweden)

    Daniel I. Massé

    2014-12-01

    Full Text Available The specific objectives of this experiment were to investigate the effects of adding 10% or 30% corn dried distillers grains with solubles (DDGS to the dairy cow diet and the effects of bedding type (wood shavings, straw or peat moss in dairy slurry on fugitive CH4 emissions. The addition of DDGS10 to the dairy cow diet significantly increased (29% the daily amount of fat excreted in slurry compared to the control diet. The inclusion of DDGS30 in the diet increased the daily amounts of excreted DM, volatile solids (VS, fat, neutral detergent fiber (NDF, acid detergent fiber (ADF and hemicellulose by 18%, 18%, 70%, 30%, 15% and 53%, respectively, compared to the control diet. During the storage experiment, daily fugitive CH4 emissions showed a significant increase of 15% (p < 0.05 for the slurry resulting from the corn DDGS30 diet. The addition of wood shavings and straw did not have a significant effect on daily fugitive CH4 emissions relative to the control diet, whereas the addition of peat moss caused a significant increase of 27% (p < 0.05 in fugitive CH4 emissions.

  4. Effects of Adding Corn Dried Distiller Grains with Solubles (DDGS) to the Dairy Cow Diet and Effects of Bedding in Dairy Cow Slurry on Fugitive Methane Emissions.

    Science.gov (United States)

    Massé, Daniel I; Jarret, Guillaume; Benchaar, Chaouki; Hassanat, Fadi

    2014-12-09

    The specific objectives of this experiment were to investigate the effects of adding 10% or 30% corn dried distillers grains with solubles (DDGS) to the dairy cow diet and the effects of bedding type (wood shavings, straw or peat moss) in dairy slurry on fugitive CH₄ emissions. The addition of DDGS10 to the dairy cow diet significantly increased (29%) the daily amount of fat excreted in slurry compared to the control diet. The inclusion of DDGS30 in the diet increased the daily amounts of excreted DM, volatile solids (VS), fat, neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose by 18%, 18%, 70%, 30%, 15% and 53%, respectively, compared to the control diet. During the storage experiment, daily fugitive CH₄ emissions showed a significant increase of 15% (p < 0.05) for the slurry resulting from the corn DDGS30 diet. The addition of wood shavings and straw did not have a significant effect on daily fugitive CH₄ emissions relative to the control diet, whereas the addition of peat moss caused a significant increase of 27% (p < 0.05) in fugitive CH₄ emissions.

  5. 40 CFR 63.7293 - What work practice standards must I meet for fugitive pushing emissions if I have a non-recovery...

    Science.gov (United States)

    2010-07-01

    ... meet for fugitive pushing emissions if I have a non-recovery coke oven battery? 63.7293 Section 63.7293... Standards for Hazardous Air Pollutants for Coke Ovens: Pushing, Quenching, and Battery Stacks Emission... pushing emissions if I have a non-recovery coke oven battery? (a) You must meet the requirements in...

  6. Fractal dust grains in plasma

    International Nuclear Information System (INIS)

    Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

    2012-01-01

    Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

  7. Characteristics of PM10 Chemical Source Profiles for Geological Dust from the South-West Region of China

    Directory of Open Access Journals (Sweden)

    Yayong Liu

    2016-11-01

    Full Text Available Ninety-six particulate matter (PM10 chemical source profiles for geological sources in typical cities of southwest China were acquired from Source Profile Shared Service in China. Twenty-six elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sn, Sb, Ba, Be, Tl and Pb, nine ions (F−, Cl−, SO42−, NO3−, Na+, NH4+, K+, Mg2+ and Ca2+, and carbon-containing species (organic carbon and elemental carbon were determined to construct these profiles. Individual source profiles were averaged and compared to quantify similarities and differences in chemical abundances using the profile-compositing method. Overall, the major components of PM10 in geological sources were crustal minerals and undefined fraction. Different chemical species could be used as tracers for various types of geological dust in the region that resulted from different anthropogenic influence. For example, elemental carbon, V and Zn could be used as tracers for urban paved road dust; Al, Si, K+ and NH4+ for agricultural soil; Al and Si for natural soil; and SO42− for urban resuspended dust. The enrichment factor analysis showed that Cu, Se, Sr and Ba were highly enriched by human activities in geological dust samples from south-west China. Elemental ratios were taken to highlight the features of geological dust from south-west China by comparing with northern urban fugitive dust, loess and desert samples. Low Si/Al and Fe/Al ratios can be used as markers to trace geological sources from southwestern China. High Pb/Al and Zn/Al ratios observed in urban areas demonstrated that urban geological dust was influenced seriously by non-crustal sources.

  8. Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China.

    Science.gov (United States)

    Yang, Jie; Teng, Yanguo; Song, Liuting; Zuo, Rui

    2016-01-01

    Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn). The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment) > Zn, Ni, Cr, Fe, and Mn (moderate enrichment) > Cd and Ni (minimal enrichment). Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area.

  9. Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China.

    Directory of Open Access Journals (Sweden)

    Jie Yang

    Full Text Available Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn. The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment > Zn, Ni, Cr, Fe, and Mn (moderate enrichment > Cd and Ni (minimal enrichment. Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area.

  10. Sahara Dust Cloud

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Dust Particles Click on the image for Quicktime movie from 7/15-7/24 A continent-sized cloud of hot air and dust originating from the Sahara Desert crossed the Atlantic Ocean and headed towards Florida and the Caribbean. A Saharan Air Layer, or SAL, forms when dry air and dust rise from Africa's west coast and ride the trade winds above the Atlantic Ocean. These dust clouds are not uncommon, especially during the months of July and August. They start when weather patterns called tropical waves pick up dust from the desert in North Africa, carry it a couple of miles into the atmosphere and drift westward. In a sequence of images created by data acquired by the Earth-orbiting Atmospheric Infrared Sounder ranging from July 15 through July 24, we see the distribution of the cloud in the atmosphere as it swirls off of Africa and heads across the ocean to the west. Using the unique silicate spectral signatures of dust in the thermal infrared, AIRS can detect the presence of dust in the atmosphere day or night. This detection works best if there are no clouds present on top of the dust; when clouds are present, they can interfere with the signal, making it much harder to detect dust as in the case of July 24, 2005. In the Quicktime movie, the scale at the bottom of the images shows +1 for dust definitely detected, and ranges down to -1 for no dust detected. The plots are averaged over a number of AIRS observations falling within grid boxes, and so it is possible to obtain fractional numbers. [figure removed for brevity, see original site] Total Water Vapor in the Atmosphere Around the Dust Cloud Click on the image for Quicktime movie The dust cloud is contained within a dry adiabatic layer which originates over the Sahara Desert. This Saharan Air Layer (SAL) advances Westward over the Atlantic Ocean, overriding the cool, moist air nearer the surface. This burst of very dry air is visible in the AIRS retrieved total water

  11. Electrodynamic Dust Shield Demonstrator

    Science.gov (United States)

    Stankie, Charles G.

    2013-01-01

    The objective of the project was to design and manufacture a device to demonstrate a new technology developed by NASA's Electrostatics and Surface Physics Laboratory. The technology itself is a system which uses magnetic principles to remove regolith dust from its surface. This project was to create an enclosure that will be used to demonstrate the effectiveness of the invention to The Office of the Chief Technologist. ONE of the most important challenges of space exploration is actually caused by something very small and seemingly insignificant. Dust in space, most notably on the moon and Mars, has caused many unforeseen issues. Dirt and dust on Earth, while a nuisance, can be easily cleaned and kept at bay. However, there is considerably less weathering and erosion in space. As a result, the microscopic particles are extremely rough and abrasive. They are also electrostatically charged, so they cling to everything they make contact with. This was first noted to be a major problem during the Apollo missions. Dust would stick to the spacesuits, and could not be wiped off as predicted. Dust was brought back into the spacecraft, and was even inhaled by astronauts. This is a major health hazard. Atmospheric storms and other events can also cause dust to coat surfaces of spacecraft. This can cause abrasive damage to the craft. The coating can also reduce the effectiveness of thermal insulation and solar panels.' A group of engineers at Kennedy Space Center's Electrostatics and Surface Physics Laboratory have developed a new technology, called the Electrodynamic Dust Shield, to help alleviate these problems. It is based off of the electric curtain concept developed at NASA in 1967. "The EDS is an active dust mitigation technology that uses traveling electric fields to transport electrostatically charged dust particles along surfaces. To generate the traveling electric fields, the EDS consists of a multilayer dielectric coating with an embedded thin electrode grid

  12. Evaluation and modelling of haul road dust palliatives

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, R.J.; Visser, A.T.

    2000-07-01

    Excessive dust generation from mine haul roads is a problem common to most surface coal mining operations. Optimal warning course material selection parameters reduce, but do not totally eliminate the potential to produce dust. For existing operations, which may not have optimally designed and maintained roads, the problem of identifying existing deficiencies, quantifying their impact and assigning priorities within the constraints of limited capital and manpower is problematic. This is reflected in the fact that most surface mine operators agree dust-free roads are desirable, but find it difficult to translate this into cost-effective betterment activities. This paper describes a dust palliative evaluation, management and costing strategy. Models are described which enable mines to assess the likely dustiness of their chosen wearing course materials as a function of surface loading of fines, traffic types and volume, together with various material parameters. These models are then combined with palliative suppression performance models to enable predictions to be made concerning the suppression- and cost-efficiency of various dust palliation options. 13 refs., 5 figs., 4 tabs.

  13. Dust in planetary nebulae

    International Nuclear Information System (INIS)

    Kwok, S.

    1980-01-01

    A two-component dust model is suggested to explain the infrared emission from planetary nebulae. A cold dust component located in the extensive remnant of the red-giant envelope exterior to the visible nebula is responsible for the far-infrared emission. A ward dust component, which is condensed after the formation of the planetary nebula and confined within the ionized gas shell, emits most of the near- and mid-infrared radiation. The observations of NGC 7027 are shown to be consisten with such a model. The correlation of silicate emission in several planetary nebulae with an approximately +1 spectral index at low radio frequencies suggests that both the silicate and radio emissions originate from the remnant of the circumstellar envelope of th precursor star and are observable only while the planetary nebula is young. It is argued that oxygen-rich stars as well as carbon-rich stars can be progenitors of planetary nebulae

  14. Interstellar dust and extinction

    International Nuclear Information System (INIS)

    Mathis, J.S.

    1990-01-01

    It is noted that the term interstellar dust refers to materials with rather different properties, and that the mean extinction law of Seaton (1979) or Savage and Mathis (1979) should be replaced by the expression given by Cardelli et al. (1989), using the appropriate value of total-to-selective extinction. The older laws were appropriate for the diffuse ISM but dust in clouds differs dramatically in its extinction law. Dust is heavily processed while in the ISM by being included within clouds and cycled back into the diffuse ISM many times during its lifetime. Hence, grains probably reflect only a trace of their origin, although meteoritic inclusions with isotopic anomalies demonstrate that some tiny particles survive intact from a supernova origin to the present. 186 refs

  15. Dust control for draglines

    Energy Technology Data Exchange (ETDEWEB)

    Grad, P.

    2009-09-15

    Monitoring dust levels inside draglines reveals room for improvement in how filtration systems are used and maintained. The Australian firm BMT conducted a field test program to measure airflow parameters, dust fallout rates and dust concentrations, inside and outside the machine house, on four draglines and one shovel. The study involved computational fluid dynamics (CFD) simulations. The article describes how the tests were made and gives results. It was not possible to say which of the two main filtration systems currently used on Australian draglines - Dynavane or Floseps - performs better. It would appear that more frequent maintenance and cleaning would increase the overall filtration performance and systems could be susceptible to repeat clogging in a short time. 2 figs., 1 photos.

  16. DustEM: Dust extinction and emission modelling

    Science.gov (United States)

    Compiègne, M.; Verstraete, L.; Jones, A.; Bernard, J.-P.; Boulanger, F.; Flagey, N.; Le Bourlot, J.; Paradis, D.; Ysard, N.

    2013-07-01

    DustEM computes the extinction and the emission of interstellar dust grains heated by photons. It is written in Fortran 95 and is jointly developed by IAS and CESR. The dust emission is calculated in the optically thin limit (no radiative transfer) and the default spectral range is 40 to 108 nm. The code is designed so dust properties can easily be changed and mixed and to allow for the inclusion of new grain physics.

  17. Effect of cement dust pollution on certain physical parameters of maize crop and soils

    Energy Technology Data Exchange (ETDEWEB)

    Parthasarathy, S; Arunachalam, N; Natarajan, K; Oblisami, G; Rangaswami, G

    1975-04-01

    A study was undertaken in the fields near a cement factory where the cement dust is the prime pollutant to the field crops and soils. Cement dust deposit varied with the distance from the kiln and fourth and fifth leaves of maize had comparatively more dust than the first three leaves from the top. The cement dust deposited plants showed a suppression in most of the characters like leaf size, number and size of cobs and plant height when compared to plants in non-polluted fields. On comparison with the physical characters of the soils from the control field the soil from cement dust polluted field showed a decrease in water holding capacity and pore space while thermal conductivity and specific heat were more. Artificial mixtures of red and black soils with cement dust showed similar trend as those of the field sample, the black soil being affected more seriously than the red soil.

  18. Dust-Plasma Interactions

    International Nuclear Information System (INIS)

    Rosenberg, M.

    2010-01-01

    The objective of our theoretical research under this grant over the past 3 years was to develop new understanding in a range of topics in the physics of dust-plasma interactions, with application to space and the laboratory. We conducted studies related to the physical properties of dust, waves and instabilities in both weakly coupled and strongly coupled dusty plasmas, and innovative possible applications. A major consideration in our choice of topics was to compare theory with experiments or observations, and to motivate new experiments, which we believe is important for developing this relatively new field. Our research is summarized, with reference to our list of journal publications.

  19. New approaches to dust mitigation in the Antelope Valley

    Energy Technology Data Exchange (ETDEWEB)

    Farber, R.J.; Kim, B.M.; Grantz, D.A.; Vaughn, D.L.; Zink, T.; Skadberg, K.; Cowherd, C.; Grelinger, M.A.; Campbell, R.; De Salvio, A.; VanCuren, T.; Bort, J.

    1999-07-01

    The arid deserts of the southwestern US experience a frequent dust problem which can lead to PM10 violations. Blowing dust is also one of the major air quality problems of the arid deserts. From 1992 through the present, a group of research scientists have been investigating new techniques for mitigating the windblown dust in the Mojave Desert and more specifically the Antelope Valley near Palmdale and Lancaster, CA. This paper summarizes the progress made toward dust suppression in the Antelope Valley during the initial research phase from 1992 through 1996. During this period, there were both successes and failures. Stabilizing disturbed desert lands in a water-starved environment is challenging. The initial attempts focused on revegetation of native plants by seedings. There were mixed results depending on both the magnitude and timing of the rainfall. Various types of windfences were also erected and their effectiveness was studied using BSNE's. In the present program, the objectives have been broadened to include mitigating dust from all types of disturbed lands, not only abandoned farmlands. Techniques include new approaches to revegetation using seedlings, varying water treatments and soil amendments. An array of chemical suppressants are also being evaluated for cost-effectiveness as a function of longevity. Various geometries of wind fences have also been erected in blow sand areas and are being evaluated for cost-effectiveness using an interesting evaluation scheme. This portion of the paper provides a progress report of these latest dust mitigation techniques. This current research program is due to conclude about 2002. The end product of this decade research program will be a cookbook of dust mitigation solutions for various users including regulatory agencies, the USDA NRCS, farmers and construction interests.

  20. Control of harmful dust in coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Goddard, B; Bower, K; Mitchell, D

    1973-01-01

    This handbook consists of a series of short chapters devoted to: sources of airborne dust; dust standards and methods of sampling; dust prevention on mechanized faces; ventilation and dust extraction; distribution and use of water; dust control on mechanized faces; dust control in drivages and headings; drilling and shotfiring; dust control in transport; some outbye dust control techniques (hygroscopic salts, impingement curtains); water infusion; personal protective equipment. (CIS Abstr.)

  1. Energy conservation and dust production in wet rotary cement kilns

    Energy Technology Data Exchange (ETDEWEB)

    Sell, N J; Fischbach, F A

    1976-12-01

    Energy conservation is currently a major concern of the cement industry. A comparison of data supplied by the U.S. Federal Energy Administration with that gathered in an extensive private study incorporating 29 wet cement plants indicates that a significant reduction of the energy consumed can be accomplished by decreasing the amount of dust generated in the process. Energy saving of 8 percent through dust suppression appears possible by increasing the slurry moisture and by using hammermills rather than impactors as the crushing technique.

  2. Dust evolution in protoplanetary disks

    OpenAIRE

    Gonzalez , Jean-François; Fouchet , Laure; T. Maddison , Sarah; Laibe , Guillaume

    2007-01-01

    6 pages, 5 figures, to appear in the Proceedings of IAU Symp. 249: Exoplanets: Detection, Formation and Dynamics (Suzhou, China); International audience; We investigate the behaviour of dust in protoplanetary disks under the action of gas drag using our 3D, two-fluid (gas+dust) SPH code. We present the evolution of the dust spatial distribution in global simulations of planetless disks as well as of disks containing an already formed planet. The resulting dust structures vary strongly with pa...

  3. Respirable versus inhalable dust sampling

    International Nuclear Information System (INIS)

    Hondros, J.

    1987-01-01

    The ICRP uses a total inhalable dust figure as the basis of calculations on employee lung dose. This paper was written to look at one aspect of the Olympic Dam dust situation, namely, the inhalable versus respirable fraction of the dust cloud. The results of this study will determine whether it is possible to use respirable dust figures, as obtained during routine monitoring to help in the calculations of employee exposure to internal radioactive contaminants

  4. Paleo-dust insights onto dust-climate interactions

    Science.gov (United States)

    Albani, S.; Mahowald, N. M.

    2017-12-01

    Mineral dust emissions are affected by changing climate conditions, and in turn dust impacts the atmospheric radiation budget, clouds and biogeochemical cycles. Climate and public health dust-related issues call for attention on the fate of the dust cycle in the future, and the representation of the dust cycle is now part of the strategy of the Paleoclimate Modelling Intercomparison Project phase 4 and the Coupled Model Intercomparison Project phase 6 (PMIP4-CMIP6). Since mineral aerosols are one of the most important natural aerosols, understanding past dust responses to climate in the paleoclimate will allow us to better understand mineral aerosol feedbacks with climate and biogeochemistry in the Anthropocene. Modern observations and paleoclimate records offer the possibility of multiple, complementary views on the global dust cycle, and allow to validate and/or constrain the numerical representation of dust in climate and Earth system models. We present our results from a set of simulations with the Community Earth System Model for different climate states, including present and past climates such as the pre-industrial, the mid-Holocene and the Last Glacial Maximum. A set of simulations including a prognostic dust cycle was thoroughly compared with a wide set of present day observations from different platforms and regions, in order to realistically constrain the magnitude of dust load, surface concentration, deposition, optical properties, and particle size distributions. The magnitude of emissions for past climate regimes was constrained based on compilations of paleodust mass accumulation rates and size distributions, as well as based on information on dust provenance. The comparison with a parallel set of simulations without dust allows estimating the impacts of dust on surface climate. We analyze impacts of dust on the mean and variability of surface temperature and precipitation in each climate state, as well as the impacts that changing dust emissions had

  5. Evaluation of methane fugitive emissions in systems of natural gas transportation. The Bolivia-Brazil pipeline case; Avaliacao das emissoes fugitivas de metano em sistemas de transporte de gas natural. O caso do gasoduto Bolivia-Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Daniele Mesquita Bordalo da; La Rovere, Emilio Lebre [Universidade Federal do Rio de Janeiro (PPE/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Planejamento Energetico], Emails: danielembc@poli.ufrj.br, emilio@ppe.ufrj.br; Sarno, Ruy Alberto Campos [Transportadora Brasileira Gasoduto Bolivia-Brasil S.A., Rio de Janeiro, RJ (Brazil)], E-mail: ruy@tbg.com.br

    2010-07-01

    This paper verifies the total annual of fugitive emissions of methane from the Bolivia-Brazil pipeline, presently the largest pipeline in operation in Brazil, beside to estimate the financial loss associated to those emissions.

  6. Erosion of dust aggregates

    NARCIS (Netherlands)

    Seizinger, A.; Krijt, S.; Kley, W.

    2013-01-01

    Aims: The aim of this work is to gain a deeper insight into how much different aggregate types are affected by erosion. Especially, it is important to study the influence of the velocity of the impacting projectiles. We also want to provide models for dust growth in protoplanetary disks with simple

  7. Dust-Plasma Interactions

    International Nuclear Information System (INIS)

    Rosenberg, Marelene

    2005-01-01

    Our theoretical research on dust-plasma interactions has concentrated on three main areas: (a)studies of grain charging and applications; (b) waves and instabilities in weakly correlated dusty plasma with applications to space and laboratory plasmas; (c) waves in strongly coupled dusty plasmas.

  8. From dust to life

    Science.gov (United States)

    Wickramasinghe, Chandra

    After initially challenging the dirty-ice theory of interstellar grains, Fred Hoyle and the present author proposed carbon (graphite) grains, mixtures of refractory grains, organic polymers, biochemicals and finally bacterial grains as models of interstellar dust. The present contribution summarizes this trend and reviews the main arguments supporting a modern version of panspermia.

  9. The impact of Saharan Dust on the genesis and evolution of Hurricane Earl (2010)

    Science.gov (United States)

    Pan, B.; Wang, Y.; Hsieh, J. S.; Lin, Y.; Hu, J.; Zhang, R.

    2017-12-01

    Dust, one of the most abundant natural aerosols, can exert substantial radiative and microphysical effects on the regional climate and has potential impacts on the genesis and intensification of tropical cyclones (TCs). A Weather Research and Forecasting Model and the Regional Oceanic Modeling System coupled model (WRF-ROMS) is used to simulate the evolution of Hurricane Earl (2010), of which Earl was interfered by Saharan dust at the TC genesis stage. A new dust module has been implemented to the TAMU two-moment microphysics scheme in the WRF model. It accounts for both dust as Cloud Condensation Nuclei (CCN) and Ice Nuclei (IN). The hurricane track, intensity and precipitation have been compared to the best track data and TRMM precipitation, respectively. The influences of Saharan dust on Hurricane Earl are investigated with dust-CCN, dust-IN, and dust-free scenarios. The analysis shows that Saharan dust changes the latent heat and moisture distribution, invigorates the convections in the hurricane's eyewall, and suppresses the development of Earl. This finding addresses the importance of accounting dust microphysics effect on hurricane predictions.

  10. Metal dusting of low alloy steels

    Energy Technology Data Exchange (ETDEWEB)

    Grabke, H.J. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)); Bracho-Troconis, C.B. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)); Mueller-Lorenz, E.M. (Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany))

    1994-04-01

    The metal dusting of two low alloy steels was investigated at 475 C in flowing CO-H[sub 2]-H[sub 2]O mixtures at atmospheric pressure with a[sub C] > 1. The reaction sequence comprises: (1) oversaturation with C, formation of cementite and its decomposition to metal particles and carbon, and (2) additional carbon deposition on the metal particles from the atmosphere. The metal wastage rate r[sub 1] was determined by analysis of the corrosion product after exposures, this rate is constant with time and virtually independent of the environment. The carbon deposition from the atmosphere was determined by thermogravimetry, its rate r[sub 2] increases linearly with time, which can be explained by the catalytic action of the metal particles - periodic changes are superposed. The rate of carbon deposition r[sub 2] is proportional to the carbon activity in the atmosphere. The metal dusting could not be suppressed by increasing the oxygen activity or preoxidation, even if magnetite should be stable. Addition of H[sub 2]S, however, effectively suppresses the attack. (orig.)

  11. Modelling dust transport in tokamaks

    International Nuclear Information System (INIS)

    Martin, J.D.; Martin, J.D.; Bacharis, M.; Coppins, M.; Counsell, G.F.; Allen, J.E.; Counsell, G.F.

    2008-01-01

    The DTOKS code, which models dust transport through tokamak plasmas, is described. The floating potential and charge of a dust grain in a plasma and the fluxes of energy to and from it are calculated. From this model, the temperature of the dust grain can be estimated. A plasma background is supplied by a standard tokamak edge modelling code (B2SOLPS5.0), and dust transport through MAST (the Mega-Amp Spherical Tokamak) and ITER plasmas is presented. We conclude that micron-radius tungsten dust can reach the separatrix in ITER. (authors)

  12. Cooling Timescale of Dust Tori in Dying Active Galactic Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ichikawa, Kohei [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Tazaki, Ryo, E-mail: k.ichikawa@astro.columbia.edu [Astronomical Institute, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

    2017-07-20

    We estimate the dust torus cooling timescale once the active galactic nucleus (AGN) is quenched. In a clumpy torus system, once the incoming photons are suppressed, the cooling timescale of one clump from T {sub dust} = 1000 K to several 10 K is less than 10 years, indicating that the dust torus cooling time is mainly governed by the light crossing time of the torus from the central engine. After considering the light crossing time of the torus, the AGN torus emission at 12 μ m becomes over two orders of magnitude fainter within 100 years after the quenching. We also propose that those “dying” AGNs could be found using the AGN indicators with a different physical scale R such as 12 μ m band luminosity tracing AGN torus ( R ∼ 10 pc) and the optical [O iii] λ 5007 emission line tracing narrow line regions ( R = 10{sup 2–4} pc).

  13. Lithium Wall Conditioning And Surface Dust Detection On NSTX

    International Nuclear Information System (INIS)

    Skinner, C.H.; Allain, J.P.; Bell, M.G.; Friesen, F.Q.L.; Heim, B.; Jaworski, M.A.; Kugel, H.; Maingi, R.; Rais, B.; Taylor, C.N.

    2011-01-01

    Lithium evaporation onto NSTX plasma facing components (PFC) has resulted in improved energy confinement, and reductions in the number and amplitude of edge-localized modes (ELMs) up to the point of complete ELM suppression. The associated PFC surface chemistry has been investigated with a novel plasma material interface probe connected to an in-vacuo surface analysis station. Analysis has demonstrated that binding of D atoms to the polycrystalline graphite material of the PFCs is fundamentally changed by lithium - in particular deuterium atoms become weakly bonded near lithium atoms themselves bound to either oxygen or the carbon from the underlying material. Surface dust inside NSTX has been detected in real-time using a highly sensitive electrostatic dust detector. In a separate experiment, electrostatic removal of dust via three concentric spiral-shaped electrodes covered by a dielectric and driven by a high voltage 3-phase waveform was evaluated for potential application to fusion reactors

  14. Saharan Dust, Transport Processes, and Possible Impacts on Hurricane Activities

    Science.gov (United States)

    Lau, William K. M.; Kim, K. M.

    2010-01-01

    In this paper, we present observational evidence of significant relationships between Saharan dust outbreak, and African Easterly wave activities and hurricane activities. We found two dominant paths of transport of Saharan dust: a northern path, centered at 25degN associated with eastward propagating 6-19 days waves over northern Africa, and a southern path centered at 15degN, associated with the AEW, and the Atlantic ITCZ. Seasons with stronger dust outbreak from the southern path are associated with a drier atmosphere over the Maximum Development Region (MDR) and reduction in tropical cyclone and hurricane activities in the MDR. Seasons with stronger outbreak from the northern path are associated with a cooler N. Atlantic, and suppressed hurricane in the western Atlantic basin.

  15. Dust storm, northern Mexico

    Science.gov (United States)

    1983-01-01

    This large dust storm along the left side of the photo, covers a large portion of the state of Coahuila, Mexico (27.5N, 102.0E). The look angle of this oblique photo is from the south to the north. In the foreground is the Sierra Madre Oriental in the states Coahuila and Nuevo Leon with the Rio Grande River, Amistad Reservoir and Texas in the background.

  16. Dust acoustic shock wave at high dust density

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Sarkar, Susmita; Khan, Manoranjan; Avinash, K.; Gupta, M. R.

    2003-01-01

    Dust acoustic (DA) shock wave at high dust density, i.e., the dust electroacoustic (DEA) or dust Coulomb (DC) shock wave has been investigated incorporating the nonadiabatic dust charge variation. The nonlinear DEA (DC) shock wave is seen to be governed by the Korteweg-de Vries Burger equation, in which the Burger term is proportional to the nonadiabaticity generated dissipation. It is seen that the shock strength decreases but after reaching minimum, it increases as the dust space charge density |q d n d | increases and the shock strength of DA wave is greater than that of DEA (DC) wave. Moreover the DEA (DC) shock width increases appreciably with increase mass m i of the ion component of the dusty plasma but for DA shock wave the effect is weak

  17. Dust, Climate, and Human Health

    Science.gov (United States)

    Maynard, Nancy G.

    2003-01-01

    Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. This paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health.

  18. Parameterizing the interstellar dust temperature

    Science.gov (United States)

    Hocuk, S.; Szűcs, L.; Caselli, P.; Cazaux, S.; Spaans, M.; Esplugues, G. B.

    2017-08-01

    The temperature of interstellar dust particles is of great importance to astronomers. It plays a crucial role in the thermodynamics of interstellar clouds, because of the gas-dust collisional coupling. It is also a key parameter in astrochemical studies that governs the rate at which molecules form on dust. In 3D (magneto)hydrodynamic simulations often a simple expression for the dust temperature is adopted, because of computational constraints, while astrochemical modelers tend to keep the dust temperature constant over a large range of parameter space. Our aim is to provide an easy-to-use parametric expression for the dust temperature as a function of visual extinction (AV) and to shed light on the critical dependencies of the dust temperature on the grain composition. We obtain an expression for the dust temperature by semi-analytically solving the dust thermal balance for different types of grains and compare to a collection of recent observational measurements. We also explore the effect of ices on the dust temperature. Our results show that a mixed carbonaceous-silicate type dust with a high carbon volume fraction matches the observations best. We find that ice formation allows the dust to be warmer by up to 15% at high optical depths (AV> 20 mag) in the interstellar medium. Our parametric expression for the dust temperature is presented as Td = [ 11 + 5.7 × tanh(0.61 - log 10(AV) ]χuv1/5.9, where χuv is in units of the Draine (1978, ApJS, 36, 595) UV field.

  19. Dust in H II regions

    International Nuclear Information System (INIS)

    Isobe, S.

    1977-01-01

    Several pieces of evidence indicate that H II regions may contain dust: 1) the continuum light scattered by dust grains (O'Dell and Hubbard, 1965), 2) thermal radiation from dust grains at infrared wavelengths (Ney and Allen, 1969), 3) the abnormal helium abundance in some H II regions (Peimbert and Costero, 1969), etc. Although observations of the scattered continuum suggest that the H II region cores may be dust-free, dust grains and gas must be well mixed in view of the infrared observations. This difficulty may be solved by introducing globules with sizes approximately 0.001 pc. These globules and the molecular clouds adjacent to H II regions are the main sources supplying dust to H II regions. (Auth.)

  20. Large Aperture Electrostatic Dust Detector

    International Nuclear Information System (INIS)

    Skinner, C.H.; Hensley, R.; Roquemore, A.L.

    2007-01-01

    Diagnosis and management of dust inventories generated in next-step magnetic fusion devices is necessary for their safe operation. A novel electrostatic dust detector, based on a fine grid of interlocking circuit traces biased to 30 or 50 v has been developed for the detection of dust particles on remote surfaces in air and vacuum environments. Impinging dust particles create a temporary short circuit and the resulting current pulse is recorded by counting electronics. Up to 90% of the particles are ejected from the grid or vaporized suggesting the device may be useful for controlling dust inventories. We report measurements of the sensitivity of a large area (5x5 cm) detector to microgram quantities of dust particles and review its applications to contemporary tokamaks and ITER.

  1. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado and Utah using mobile stable isotope (13CH4) analysis

    Science.gov (United States)

    Rella, Chris; Jacobson, Gloria; Crosson, Eric; Karion, Anna; Petron, Gabrielle; Sweeney, Colm

    2013-04-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation. However, given that the global warming potential of methane is many times greater than that of carbon dioxide (Solomon et al. 2007), the importance of quantifying the fugitive emissions of methane throughout the natural gas production and distribution process becomes clear (Howarth et al. 2011). A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis. In particular, the 13CH4 signature of natural gas (-35 to -40 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-45 to -70 permil). In this paper we present measurements of mobile field 13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in two intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, and the Uintah basin in Utah. Mobile isotope measurements in the nocturnal boundary layer have been made, over a total path of 100s of km throughout the regions, allowing spatially resolved measurements of the regional isotope signature. Secondly, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in these regions, by making measurements of the isotope ratio directly in the downwind plume from each source. These

  2. Photoelectric charging of dust grains

    International Nuclear Information System (INIS)

    Ignatov, A. M.

    2009-01-01

    Photoemission from the surface of a dust grain in vacuum is considered. It is shown that the cutoff in the energy spectrum of emitted electrons leads to the formation of a steady-state electron cloud. The equation describing the distribution of the electric potential in the vicinity of a dust grain is solved numerically. The dust grain charge is found as a function of the grain size.

  3. Dust in cosmic plasma environments

    International Nuclear Information System (INIS)

    Mendis, D.A.

    1979-01-01

    Cosmic dust is invariably immersed in a plasma and a radiative environment. Consequently, it is charged to some electrostatic potential which depends on the properties of the environment as well as the nature of the dust. This charging affects the physical and dynamical properties of the dust. In this paper the basic aspects of this dust-plasma interaction in several cosmic environments - including planetary magnetospheres, the heliosphere and the interstellar medium - are discussed. The physical and dynamical consequences of the interaction, as well as the pertinent observational evidence, are reviewed. Finally, the importance of the surface charge during the condensation process in plasma environments is stressed. (Auth.)

  4. The HOSTS Survey—Exozodiacal Dust Measurements for 30 Stars

    Science.gov (United States)

    Ertel, S.; Defrère, D.; Hinz, P.; Mennesson, B.; Kennedy, G. M.; Danchi, W. C.; Gelino, C.; Hill, J. M.; Hoffmann, W. F.; Rieke, G.; Shannon, A.; Spalding, E.; Stone, J. M.; Vaz, A.; Weinberger, A. J.; Willems, P.; Absil, O.; Arbo, P.; Bailey, V. P.; Beichman, C.; Bryden, G.; Downey, E. C.; Durney, O.; Esposito, S.; Gaspar, A.; Grenz, P.; Haniff, C. A.; Leisenring, J. M.; Marion, L.; McMahon, T. J.; Millan-Gabet, R.; Montoya, M.; Morzinski, K. M.; Pinna, E.; Power, J.; Puglisi, A.; Roberge, A.; Serabyn, E.; Skemer, A. J.; Stapelfeldt, K.; Su, K. Y. L.; Vaitheeswaran, V.; Wyatt, M. C.

    2018-05-01

    The Hunt for Observable Signatures of Terrestrial Systems survey searches for dust near the habitable zones (HZs) around nearby, bright main-sequence stars. We use nulling interferometry in the N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early-type and Sun-like stars, but decrease from {60}-21+16% for stars with previously detected cold dust to {8}-3+10% for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focusing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable Large Binocular Telescope Interferometer (LBTI) excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are limited so far, and extending the survey is critical to informing the design of future exo-Earth imaging surveys.

  5. Mobile sensing of point-source fugitive methane emissions using Bayesian inference: the determination of the likelihood function

    Science.gov (United States)

    Zhou, X.; Albertson, J. D.

    2016-12-01

    Natural gas is considered as a bridge fuel towards clean energy due to its potential lower greenhouse gas emission comparing with other fossil fuels. Despite numerous efforts, an efficient and cost-effective approach to monitor fugitive methane emissions along the natural gas production-supply chain has not been developed yet. Recently, mobile methane measurement has been introduced which applies a Bayesian approach to probabilistically infer methane emission rates and update estimates recursively when new measurements become available. However, the likelihood function, especially the error term which determines the shape of the estimate uncertainty, is not rigorously defined and evaluated with field data. To address this issue, we performed a series of near-source (using a specialized vehicle mounted with fast response methane analyzers and a GPS unit. Methane concentrations were measured at two different heights along mobile traversals downwind of the sources, and concurrent wind and temperature data are recorded by nearby 3-D sonic anemometers. With known methane release rates, the measurements were used to determine the functional form and the parameterization of the likelihood function in the Bayesian inference scheme under different meteorological conditions.

  6. Gravitational radiation from dust

    International Nuclear Information System (INIS)

    Isaacson, R.A.; Welling, J.S.; Winicour, J.

    1985-01-01

    A dust cloud is examined within the framework of the general relativistic characteristic initial value problem. Unique gravitational initial data are obtained by requiring that the space-time be quasi-Newtonian. Explicit calculations of metric and matter fields are presented, which include all post-Newtonian corrections necessary to discuss the major physical properties of null infinity. These results establish a curved space version of the Einstein quadrupole formula, in the form ''news function equals third time derivative of transverse quadrupole moment,'' for this system. However, these results imply that some weakened notion of asymptotic flatness is necessary for the description of quasi-Newtonian systems

  7. Dust coagulation in ISM

    Science.gov (United States)

    Chokshi, Arati; Tielens, Alexander G. G. M.; Hollenbach, David

    1989-01-01

    Coagulation is an important mechanism in the growth of interstellar and interplanetary dust particles. The microphysics of the coagulation process was theoretically analyzed as a function of the physical properties of the coagulating grains, i.e., their size, relative velocities, temperature, elastic properties, and the van der Waal interaction. Numerical calculations of collisions between linear chains provide the wave energy in individual particles and the spectrum of the mechanical vibrations set up in colliding particles. Sticking probabilities are then calculated using simple estimates for elastic deformation energies and for the attenuation of the wave energy due to absorption and scattering processes.

  8. Dust confinement and dust acoustic waves in a magnetized plasma

    Science.gov (United States)

    Piel, A.

    2005-10-01

    Systematic laboratory experiments on dust acoustic waves require the confinement of dust particles. Here we report on new experiments in a magnetized plasma region in front of an additional positively biased disk electrode in a background plasma which is generated in argon at 27MHz between a disk and grid electrode. The plasma diffuses through the grid along the magnetic field. The three-dimensional dust distribution is measured with a horizontal sheet of laser light and a CCD camera, which are mounted on a vertical translation stage. Depending on magnetic field and discharge current, cigar or donut-shaped dust clouds are generated, which tend to rotate about the magnetic field direction. Measurements with emissive probes show that the axial confinement of dust particles with diameters between 0.7-2 μm is achieved by a balance of ion-drag force and electric field force. Dust levitation and radial confinement is due to a strong radial electric field. Dust acoustic waves are destabilized by the ion flow or can be stimulated by a periodic bias on the disk electrode. The observed wave dispersion is compared with fluid and kinetic models of the dust acoustic wave.

  9. Gravimetric dust sampling for control purposes and occupational dust sampling.

    CSIR Research Space (South Africa)

    Unsted, AD

    1997-02-01

    Full Text Available Prior to the introduction of gravimetric dust sampling, konimeters had been used for dust sampling, which was largely for control purposes. Whether or not absolute results were achievable was not an issue since relative results were used to evaluate...

  10. Of data and dust

    CERN Multimedia

    Stephanie Hills

    2016-01-01

    The traditional image of an archive is one of dusty old boxes, books and papers. When your archive is digital, dust spells disaster. An innovative environmental sensor designed and built by a CERN IT specialist has become an essential element in the Laboratory’s data-preservation strategy.   The novel air particle monitoring sensor designed by CERN's Julien Leduc. CERN’s archive holds more than 130 petabytes of data from past and present high-energy physics experiments. Some of it is 40 years old, most of it needs to be kept forever, and all of it is held on tape cartridges (over 20,000 of them). The cartridges are held inside tape libraries with robotic arms that load them into tape drives where they can be read and written. Tape cartridges have many advantages over other data storage media, notably cost and long-term reliability, but topping the list of drawbacks is their vulnerability to contamination from airborne dust particles; a tiny piece of g...

  11. Radionuclides in house dust

    Energy Technology Data Exchange (ETDEWEB)

    Fry, F A; Green, N; Dodd, N J; Hammond, D J

    1985-04-01

    Discharges of radionuclides from the British Nuclear Fuel plc (BNFL) reprocessing plant at Sellafield in Cumbria have led to elevated concentrations radionuclides in the local environment. The major routes of exposure of the public are kept under review by the appropriate authorising Government departments and monitoring is carried out both by the departments and by BNFL itself. Recently, there has been increasing public concern about general environmental contamination resulting from the discharges and, in particular, about possible exposure of members of the public by routes not previously investigated in detail. One such postulated route of exposure that has attracted the interest of the public, the press and Parliament arises from the presence of radionuclides within houses. In view of this obvious and widespread concern, the Board has undertaken a sampling programme in a few communities in Cumbria to assess the radiological significance of this source of exposure. From the results of our study, we conclude that, although radionuclides originating rom the BNFL site can be detected in house dust, this source of contamination is a negligible route of exposure for members of the public in West Cumbria. This report presents the results of the Board's study of house dust in twenty homes in Cumbria during the spring and summer of 1984. A more intensive investigation is being carried out by Imperial College. (author)

  12. Health hazards of cement dust

    International Nuclear Information System (INIS)

    Meo, Sultan A.

    2004-01-01

    ven in the 21st century, millions of people are working daily in a dusty environment. They are exposed to different types of health hazards such as fume, gases and dust, which are risk factors in developing occupational disease. Cement industry is involved in the development of structure of this advanced and modern world but generates dust during its production. Cement dust causes lung function impairment, chronic obstructive lung disease, restrictive lung disease, pneumoconiosis and carcinoma of the lungs, stomach and colon. Other studies have shown that cement dust may enter into the systemic circulation and thereby reach the essentially all the organs of body and affects the different tissues including heart, liver, spleen, bone, muscles and hairs and ultimately affecting their micro-structure and physiological performance. Most of the studies have been previously attempted to evaluate the effects of cement dust exposure on the basis of spirometry or radiology, or both. However, collective effort describing the general effects of cement dust on different organ and systems in humans or animals, or both has not been published. Therefore, the aim of this review is to gather the potential toxic effects of cement dust and to minimize the health risks in cement mill workers by providing them with information regarding the hazards of cement dust. (author)

  13. Dust forecasting system in JMA

    International Nuclear Information System (INIS)

    Mikami, M; Tanaka, T Y; Maki, T

    2009-01-01

    JMAs dust forecasting information, which is based on a GCM dust model, is presented through the JMA website coupled with nowcast information. The website was updated recently and JMA and MOE joint 'KOSA' website was open from April 2008. Data assimilation technique will be introduced for improvement of the 'KOSA' information.

  14. Dexamethasone suppression test

    Science.gov (United States)

    DST; ACTH suppression test; Cortisol suppression test ... During this test, you will receive dexamethasone. This is a strong man-made (synthetic) glucocorticoid medicine. Afterward, your blood is drawn ...

  15. Dust in flowing magnetized plasma

    International Nuclear Information System (INIS)

    Pandey, Birendra P.; Samarian, Alex A.; Vladimirov, Sergey V.

    2009-01-01

    Plasma flows occur in almost every laboratory device and interactions of flowing plasmas with near-wall impurities and/or dust significantly affects the efficiency and lifetime of such devices. The charged dust inside the magnetized flowing plasma moves primarily under the influence of the plasma drag and electric forces. Here, the charge on the dust, plasma potential, and plasma density are calculated self-consistently. The electrons are assumed non-Boltzmannian and the effect of electron magnetization and electron-atom collisions on the dust charge is calculated in a self-consistent fashion. For various plasma magnetization parameters viz. the ratio of the electron and ion cyclotron frequencies to their respective collision frequencies, plasma-atom and ionization frequencies, the evolution of the plasma potential and density in the flow region is investigated. The variation of the dust charge profile is shown to be a sensitive function of plasma parameters. (author)

  16. Deconstructing continuous flash suppression

    OpenAIRE

    Yang, Eunice; Blake, Randolph

    2012-01-01

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in co...

  17. Dust in protoplanetary disks: observations*

    Directory of Open Access Journals (Sweden)

    Waters L.B.F.M.

    2015-01-01

    Full Text Available Solid particles, usually referred to as dust, are a crucial component of interstellar matter and of planet forming disks surrounding young stars. Despite the relatively small mass fraction of ≈1% (in the solar neighborhood of our galaxy; this number may differ substantially in other galaxies that interstellar grains represent of the total mass budget of interstellar matter, dust grains play an important role in the physics and chemistry of interstellar matter. This is because of the opacity dust grains at short (optical, UV wavelengths, and the surface they provide for chemical reactions. In addition, dust grains play a pivotal role in the planet formation process: in the core accretion model of planet formation, the growth of dust grains from the microscopic size range to large, cm-sized or larger grains is the first step in planet formation. Not only the grain size distribution is affected by planet formation. Chemical and physical processes alter the structure and chemical composition of dust grains as they enter the protoplanetary disk and move closer to the forming star. Therefore, a lot can be learned about the way stars and planets are formed by observations of dust in protoplanetary disks. Ideally, one would like to measure the dust mass, the grain size distribution, grain structure (porosity, fluffiness, the chemical composition, and all of these as a function of position in the disk. Fortunately, several observational diagnostics are available to derive constrains on these quantities. In combination with rapidly increasing quality of the data (spatial and spectral resolution, a lot of progress has been made in our understanding of dust evolution in protoplanetary disks. An excellent review of dust evolution in protoplanetary disks can be found in Testi et al. (2014.

  18. Changes in Stratiform Clouds of Mesoscale Convective Complex Introduced by Dust Aerosols

    Science.gov (United States)

    Lin, B.; Min, Q.-L.; Li, R.

    2010-01-01

    Aerosols influence the earth s climate through direct, indirect, and semi-direct effects. There are large uncertainties in quantifying these effects due to limited measurements and observations of aerosol-cloud-precipitation interactions. As a major terrestrial source of atmospheric aerosols, dusts may serve as a significant climate forcing for the changing climate because of its effect on solar and thermal radiation as well as on clouds and precipitation processes. Latest satellites measurements enable us to determine dust aerosol loadings and cloud distributions and can potentially be used to reduce the uncertainties in the estimations of aerosol effects on climate. This study uses sensors on various satellites to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective complex (MCC). A trans-Atlantic dust outbreak of Saharan origin occurring in early March 2004 is considered. For the observed MCCs under a given convective strength, small hydrometeors were found more prevalent in the dusty stratiform regions than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust regions, particularly at altitudes where heterogeneous nucleation of mineral dust prevails, further supports the observed changes of clouds and precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the size spectrum of precipitation-sized hydrometeors from heavy precipitation to light precipitation and ultimately to suppress precipitation and increase the lifecycle of cloud systems, especially over stratiform areas.

  19. COAL DUST EMISSION PROBLEM

    Directory of Open Access Journals (Sweden)

    M. M. Biliaiev

    2016-12-01

    Full Text Available Purpose. The article aims to develop 2D numerical models for the prediction of atmospheric pollution during transportation of coal in the railway car, as well as the ways to protect the environment and the areas near to the mainline from the dust emission due to the air injection installation. Methodology. To solve this problem there were developed numerical models based on the use of the equations of motion of an inviscid incompressible fluid and mass transfer. For the numerical integration of the transport equation of the pollutant the implicit alternating-triangular difference scheme was used. For numerical integration of the 2D equation for the velocity potential the method of total approximation was used. The developed numerical models are the basis of established software package. On the basis of the constructed numerical models it was carried out a computational experiment to assess the level of air pollution when transporting bulk cargo by rail when the railway car has the air injection. Findings. 2D numerical models that belong to the class «diagnostic models» were developed. These models take into account the main physical factors affecting the process of dispersion of dust pollution in the atmosphere during transportation of bulk cargo. The developed numerical models make it possible to calculate the dust loss process, taking into account the use of the air injection of the car. They require a small cost of the computer time during practical realization at the low and medium power machines. There were submitted computational calculations to determine pollutant concentrations and the formation of the zone of pollution near the train with bulk cargo in «microscale» scale taking into account the air curtains. Originality. 2D numerical models taking into account the relevant factors influencing the process of dispersion of pollutants in the atmosphere, and the formation of the zone of pollution during transportation of bulk cargo by

  20. THE ROLE OF DUST IN THE EARLY UNIVERSE. I. PROTOGALAXY EVOLUTION

    International Nuclear Information System (INIS)

    Yamasawa, Daisuke; Habe, Asao; Kozasa, Takashi; Nozawa, Takaya; Nomoto, Ken'ichi; Hirashita, Hiroyuki; Umeda, Hideyuki

    2011-01-01

    We develop one-zone galaxy formation models in the early universe, taking into account dust formation and evolution by supernova (SN) explosions. We focus on the time evolution of dust size distribution, because H 2 formation on the dust surface plays a critical role in the star formation process in the early universe. In the model, we assume that star formation rate (SFR) is proportional to the total amount of H 2 . We consistently treat (1) the formation and size evolution of dust, (2) the chemical reaction networks including H 2 formation both on the surface of dust and in gas phase, and (3) the SFR in the model. First, we find that, because of dust destruction due to both reverse and forward shocks driven by SNe, H 2 formation is more suppressed than in situations without such dust destruction. At the galaxy age of ∼0.8 Gyr, for galaxy models with virial mass M vir = 10 9 M sun and formation redshift z vir = 10, the molecular fraction is 2.5 orders of magnitude less in the model with dust destruction by both shocks than that in the model without dust destruction. Second, we show that the H 2 formation rate strongly depends on the interstellar medium (ISM) density around SN progenitors. The SFR in higher ISM density is lower, since dust destruction by reverse shocks is more effective in higher ISM density. We conclude that not only the amount but also the size distribution of dust related to star formation activity strongly affects the evolution of galaxies in the early universe.

  1. Dust of dark energy

    International Nuclear Information System (INIS)

    Lim, Eugene A.; Sawicki, Ignacy; Vikman, Alexander

    2010-01-01

    We introduce a novel class of field theories where energy always flows along timelike geodesics, mimicking in that respect dust, yet which possess non-zero pressure. This theory comprises two scalar fields, one of which is a Lagrange multiplier enforcing a constraint between the other's field value and derivative. We show that this system possesses no wave-like modes but retains a single dynamical degree of freedom. Thus, the sound speed is always identically zero on all backgrounds. In particular, cosmological perturbations reproduce the standard behaviour for hydrodynamics in the limit of vanishing sound speed. Using all these properties we propose a model unifying Dark Matter and Dark Energy in a single degree of freedom. In a certain limit this model exactly reproduces the evolution history of ΛCDM, while deviations away from the standard expansion history produce a potentially measurable difference in the evolution of structure

  2. Nonlinear screening of dust grains and structurization of dusty plasma

    International Nuclear Information System (INIS)

    Tsytovich, V. N.; Gusein-zade, N. G.

    2013-01-01

    equilibrium between plasma components when analyzing equilibrium structures. The effect of plasma screening nonlinearity on both the diffusion processes and the forces of dust drag by plasma fluxes is analyzed. It is shown how self-organized dust structures form in these processes. In the limit of very small dust grain charges, the forces acting on the dusty plasma components and the set of basic equations for stationary dust structures (with allowance for nonlinear screening) take a standard form. New qualitative effects, such as the suppression of diffusion due to ion scattering from dust grains and the formation of structures of different configurations, are described. A detailed comparison with previous results is performed. It is shown that the solution of basic nonlinear equations for dust structures yields new qualitative effects. A number of new effects to be studied in future dusty plasma experiments with the formation of structures in spherical chambers are predicted (it is assumed that diffusion will play a significant role under microgravity conditions). Recent ground-based experiments, as well as experiments carried out onboard the International Space Station, directly confirm the nonlinear character of screening and the significant role played by this nonlinearity in the structurization of dusty plasma. Experiments on the formation of structures consisting of smaller dust grains within structures formed of larger grains are discussed. It is shown that those experiments can be interpreted only using the concept of nonlinear screening

  3. Quantification of Nitrous Oxide from Fugitive Emissions by Tracer Dilution Method using a Mobile Real-time Nitrous Oxide Analyzer

    Science.gov (United States)

    Mønster, J.; Rella, C.; Jacobson, G. A.; He, Y.; Hoffnagle, J.; Scheutz, C.

    2012-12-01

    Nitrous oxide is a powerful greenhouse gas considered 298 times stronger than carbon dioxide on a hundred years term (Solomon et al. 2007). The increasing global concentration is of great concern and is receiving increasing attention in various scientific and industrial fields. Nitrous oxide is emitted from both natural and anthropogenic sources. Inventories of source specific fugitive nitrous oxide emissions are often estimated on the basis of modeling and mass balance. While these methods are well-developed, actual measurements for quantification of the emissions can be a useful tool for verifying the existing estimation methods as well as providing validation for initiatives targeted at lowering unwanted nitrous oxide emissions. One approach to performing such measurements is the tracer dilution method (Galle et al. 2001), in which a tracer gas is released at the source location at a known flow. The ratio of downwind concentrations of both the tracer gas and nitrous oxide gives the ratios of the emissions rates. This tracer dilution method can be done with both stationary and mobile measurements; in either case, real-time measurements of both tracer and analyte gas is required, which places high demands on the analytical detection method. To perform the nitrous oxide measurements, a novel, robust instrument capable of real-time nitrous oxide measurements has been developed, based on cavity ring-down spectroscopy and operating in the near-infrared spectral region. We present the results of the laboratory and field tests of this instrument in both California and Denmark. Furthermore, results are presented from measurements using the mobile plume method with a tracer gas (acetylene) to quantify the nitrous oxide and methane emissions from known sources such as waste water treatment plants and composting facilities. Nitrous oxide (blue) and methane (yellow) plumes downwind from a waste water treatment facility.

  4. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile isotopic methane analysis based on Cavity Ringdown Spectroscopy

    Science.gov (United States)

    Rella, Chris; Winkler, Renato; Sweeney, Colm; Karion, Anna; Petron, Gabrielle; Crosson, Eric

    2014-05-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of carbon dioxide emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the isotopic carbon signature to distinguish between natural gas and landfills or ruminants. We present measurements of methane using a mobile spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Performance of the CRDS isotope analyzer is presented, including precision, calibration, stability, and the potential for measurement bias due to other atmospheric constituents. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to

  5. Ulysses dust measurements near Jupiter.

    Science.gov (United States)

    Grün, E; Zook, H A; Baguhl, M; Fechtig, H; Hanner, M S; Kissel, J; Lindblad, B A; Linkert, D; Linkert, G; Mann, I B

    1992-09-11

    Submicrometer- to micrometer-sized particles were recorded by the Ulysses dust detector within 40 days of the Jupiter flyby. Nine impacts were recorded within 50 Jupiter radii with most of them recorded after closest approach. Three of these impacts are consistent with particles on prograde orbits around Jupiter and the rest are believed to have resulted from gravitationally focused interplanetary dust. From the ratio of the impact rate before the Jupiter flyby to the impact rate after the Jupiter flyby it is concluded that interplanetary dust particles at the distance of Jupiter move on mostly retrograde orbits. On 10 March 1992, Ulysses passed through an intense dust stream. The dust detector recorded 126 impacts within 26 hours. The stream particles were moving on highly inclined and apparently hyperbolic orbits with perihelion distances of >5 astronomical units. Interplanetary dust is lost rather quickly from the solar system through collisions and other mechanisms and must be almost continuously replenished to maintain observed abundances. Dust flux measurements, therefore, give evidence of the recent rates of production from sources such as comets, asteroids, and moons, as well as the possible presence of interstellar grains.

  6. Experiments on Dust Grain Charging

    Science.gov (United States)

    Abbas, M. N.; Craven, P. D.; Spann, J. F.; Tankosic, D.; LeClair, A.; West, E. A.

    2004-01-01

    Dust particles in various astrophysical environments are charged by a variety of mechanisms generally involving collisional processes with other charged particles and photoelectric emission with UV radiation from nearby sources. The sign and the magnitude of the particle charge are determined by the competition between the charging processes by UV radiation and collisions with charged particles. Knowledge of the particle charges and equilibrium potentials is important for understanding of a number of physical processes. The charge of a dust grain is thus a fundamental parameter that influences the physics of dusty plasmas, processes in the interplanetary medium and interstellar medium, interstellar dust clouds, planetary rings, cometary and outer atmospheres of planets etc. In this paper we present some results of experiments on charging of dust grains carried out on a laboratory facility capable levitating micron size dust grains in an electrodynamic balance in simulated space environments. The charging/discharging experiments were carried out by exposing the dust grains to energetic electron beams and UV radiation. Photoelectric efficiencies and yields of micron size dust grains of SiO2, and lunar simulates obtained from NASA-JSC will be presented.

  7. Graphic products used in the evaluation of traditional and emerging remote sensing technologies for the detection of fugitive contamination at selected superfund hazardous waste sites

    Science.gov (United States)

    Slonecker, E. Terrence; Fisher, Gary B.

    2011-01-01

    This report presents the overhead imagery and field sampling results used to prepare U.S. Geological Survey Open-File Report 2011-1050, 'Evaluation of Traditional and Emerging Remote Sensing Technologies for the Detection of Fugitive Contamination at Selected Superfund Hazardous Waste Sites'. These graphic products were used in the evaluation of remote sensing technology in postclosure monitoring of hazardous waste sites and represent an ongoing research effort. Soil sampling results presented here were accomplished with field portable x-ray fluoresence (XRF) technology and are used as screening tools only representing the current conditions of metals and other contaminants at selected Superfund hazardous waste sites.

  8. Triton's streaks as windblown dust

    Science.gov (United States)

    Sagan, Carl; Chyba, Christopher

    1990-01-01

    Explanations for the surface streaks observed by Voyager 2 on Triton's southern hemisphere are discussed. It is shown that, despite Triton's tenuous atmosphere, low-cohesion dust trains with diameters of about 5 micron or less may be carried into suspension by aeolian surface shear stress, given expected geostrophic wind speeds of about 10 m/s. For geyser-like erupting dust plumes, it is shown that dust-settling time scales and expected wind velocities can produce streaks with length scales in good agreement with those of the streaks. Thus, both geyserlike eruptions or direct lifting by surface winds appear to be viable mechanisms for the origin of the streaks.

  9. [Asthma due to grain dust].

    Science.gov (United States)

    Baur, X; Preisser, A; Wegner, R

    2003-06-01

    The actual literature as well as two case reports described in detail show that grain dust induces asthmatic reactions and ODTS which are obviously not of allergic origin. For diagnosis occupational-type exposure tests are decisive whereas allergological testing usually is not. Endotoxins which are present in the grain dust samples in high concentrations have to be regarded as the major causative components. To avoid irreversible lung function impairment a comprehensive early diagnosis is necessary. Generally, a remarkable reduction of exposure to dust with high levels of airborne endotoxin in agriculture has to be achieved since in many workplaces corresponding exposures are still rather high.

  10. Dust Dynamics Near Planetary Surfaces

    Science.gov (United States)

    Colwell, Joshua; Hughes, Anna; Grund, Chris

    Observations of a lunar "horizon glow" by several Surveyor spacecraft in the 1960s opened the study of the dynamics of charged dust particles near planetary surfaces. The surfaces of the Moon and other airless planetary bodies in the solar system (asteroids, and other moons) are directly exposed to the solar wind and ionizing solar ultraviolet radiation, resulting in a time-dependent electric surface potential. Because these same objects are also exposed to bombardment by micrometeoroids, the surfaces are usually characterized by a power-law size distribution of dust that extends to sub-micron-sized particles. Individual particles can acquire a charge different from their surroundings leading to electrostatic levitation. Once levitated, particles may simply return to the surface on nearly ballistic trajectories, escape entirely from the moon or asteroid if the initial velocity is large, or in some cases be stably levitated for extended periods of time. All three outcomes have observable consequences. Furthermore, the behavior of charged dust near the surface has practical implications for planned future manned and unmanned activities on the lunar surface. Charged dust particles also act as sensitive probes of the near-surface plasma environment. Recent numerical modeling of dust levitation and transport show that charged micron-sized dust is likely to accumulate in topographic lows such as craters, providing a mechanism for the creation of dust "ponds" observed on the asteroid 433 Eros. Such deposition can occur when particles are supported by the photoelectron sheath above the dayside and drift over shadowed regions of craters where the surface potential is much smaller. Earlier studies of the lunar horizon glow are consistent with those particles being on simple ballistic trajectories following electrostatic launching from the surface. Smaller particles may be accelerated from the lunar surface to high altitudes consistent with observations of high altitude

  11. Bounded dust-acoustic waves in a cylindrically bounded collisional dusty plasma with dust charge variation

    International Nuclear Information System (INIS)

    Wei Nanxia; Xue Jukui

    2006-01-01

    Taking into account the boundary, particle collisions, and dust charging effects, dust-acoustic waves in a uniform cylindrically bounded dusty plasma is investigated analytically, and the dispersion relation for the dust-acoustic wave is obtained. The effects of boundary, dust charge variation, particle collision, and dust size on the dust-acoustic wave are discussed in detail. Due to the bounded cylindrical boundary effects, the radial wave number is discrete, i.e., the spectrum is discrete. It is shown that the discrete spectrum, the adiabatic dust charge variation, dust grain size, and the particle collision have significant effects on the dust-acoustic wave

  12. Dust particle formation in silane plasmas

    NARCIS (Netherlands)

    Sorokin, M.

    2005-01-01

    Dust can be found anywhere: in the kitchen, in the car, in space… Not surprisingly we also see dust in commercial and laboratory plasmas. Dust can be introduced in the plasma, but it can also grow there by itself. In the microelectronics industry, contamination of the processing plasma by dust is an

  13. PERSPECTIVE: Dust, fertilization and sources

    Science.gov (United States)

    Remer, Lorraine A.

    2006-11-01

    Aerosols, tiny suspended particles in the atmosphere, play an important role in modifying the Earth's energy balance and are essential for the formation of cloud droplets. Suspended dust particles lifted from the world's arid regions by strong winds contain essential minerals that can be transported great distances and deposited into the ocean or on other continents where productivity is limited by lack of usable minerals [1]. Dust can transport pathogens as well as minerals great distance, contributing to the spread of human and agricultural diseases, and a portion of dust can be attributed to human activity suggesting that dust radiative effects should be included in estimates of anthropogenic climate forcing. The greenish and brownish tints in figure 1 show the wide extent of monthly mean mineral dust transport, as viewed by the MODerate resolution Imaging Spectroradiometer (MODIS) satellite sensor. The monthly mean global aerosol system for February 2006 from the MODIS aboard the Terra satellite Figure 1. The monthly mean global aerosol system for February 2006 from the MODIS aboard the Terra satellite. The brighter the color, the greater the aerosol loading. Red and reddish tints indicate aerosol dominated by small particles created primarily from combustion processes. Green and brownish tints indicate larger particles created from wind-driven processes, usually transported desert dust. Note the bright green band at the southern edge of the Saharan desert, the reddish band it must cross if transported to the southwest and the long brownish transport path as it crosses the Atlantic to South America. Image courtesy of the NASA Earth Observatory (http://earthobservatory.nasa.gov). Even though qualitatively we recognize the extent and importance of dust transport and the role that it plays in fertilizing nutrient-limited regions, there is much that is still unknown. We are just now beginning to quantify the amount of dust that exits one continental region and the

  14. Loess and Eolian Dust Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past environment derived from Loess and Eolian dust (silt-sized material deposited on the Earth surface by the surface winds. Parameter keywords describe...

  15. 75 FR 3881 - Combustible Dust

    Science.gov (United States)

    2010-01-25

    ..., rubber, drugs, dried blood, dyes, certain textiles, and metals (such as aluminum and magnesium..., furniture manufacturing, metal processing, fabricated metal products and machinery manufacturing, pesticide... standard that will comprehensively address the fire and explosion hazards of combustible dust. The Agency...

  16. Rethinking wood dust safety standards

    OpenAIRE

    Ratnasingam, Jega; Wai, Lim Tau; Ramasamy, Geetha; Ioras, Florin; Tadin, Ishak; Universiti Putra Malaysia; Buckinghamshire New University; Centre for Occupational Safety and Health Singapore

    2015-01-01

    The current universal work safety and health standards pertaining to wood dust in factories lack the localisation required. As a study has shown, there is a urgent need to reevaluate the current guidelines and practices.

  17. Evaluation of dust and trace metal estimates from the Community Multiscale Air Quality (CMAQ model version 5.0

    Directory of Open Access Journals (Sweden)

    K. W. Appel

    2013-07-01

    trace metals. Removing the anthropogenic fugitive dust (AFD emissions and the effects of wind-blown dust (WBD lowered the model soil concentrations. However, even with both AFD emissions and WBD effects removed, soil concentrations were still often overestimated, suggesting that there are other sources of errors in the modeling system that contribute to the overestimation of soil components. Efforts are underway to improve both the nighttime mixing in urban areas and the spatial and temporal distribution of dust-related emission sources in the emissions inventory.

  18. [Protecting Safety During Dust Fires and Dust Explosions - The Example of the Formosa Fun Coast Water Park Accident].

    Science.gov (United States)

    Hsieh, Ming-Hong; Wu, Jia-Wun; Li, Ya-Cing; Tang, Jia-Suei; Hsieh, Chun-Chien

    2016-02-01

    This paper will explore the fire and explosion characteristics of cornstarch powder as well as strategies for protecting the safety of people who are involved a dust fire or dust explosion. We discuss the 5 elements of dust explosions and conduct tests to analyze the fire and explosion characteristics of differently colored powders (yellow, golden yellow, pink, purple, orange and green). The results show that, while all of the tested powders were difficult to ignite, low moisture content was associated with significantly greater risks of ignition and flame spread. We found the auto-ignition temperature (AIT) of air-borne cornstarch powder to be between 385°C and 405°C, with yellow-colored cornstarch powder showing the highest AIT and pink-colored cornstarch powder showing the lowest AIT. The volume resistivity of all powder samples was approximately 108 Ω.m, indicating that they were nonconductive. Lighters and cigarettes are effective ignition sources, as their lit temperatures are higher than the AIT of cornstarch powder. In order to better protect the safety of individuals at venues where cornstarch powder is released, explosion control measures such as explosion containment facilities, vents, and explosion suppression and isolation devices should be installed. Furthermore, employees that work at these venues should be better trained in explosion prevention and control measures. We hope this article is a reminder to the public to recognize the fire and explosion characteristics of flammable powders as well as the preventive and control measures for dust explosions.

  19. Physical properties of five grain dust types.

    OpenAIRE

    Parnell, C B; Jones, D D; Rutherford, R D; Goforth, K J

    1986-01-01

    Physical properties of grain dust derived from five grain types (soybean, rice, corn, wheat, and sorghum) were measured and reported. The grain dusts were obtained from dust collection systems of terminal grain handling facilities and were assumed to be representative of grain dust generated during the handling process. The physical properties reported were as follows: particle size distributions and surface area measurements using a Coulter Counter Model TAII; percent dust fractions less tha...

  20. Efficient radiative transfer in dust grain mixtures

    OpenAIRE

    Wolf, S.

    2002-01-01

    The influence of a dust grain mixture consisting of spherical dust grains with different radii and/or chemical composition on the resulting temperature structure and spectral energy distribution of a circumstellar shell is investigated. The comparison with the results based on an approximation of dust grain parameters representing the mean optical properties of the corresponding dust grain mixture reveal that (1) the temperature dispersion of a real dust grain mixture decreases substantially ...

  1. First Real-Time Detection of Surface Dust in a Tokamak

    International Nuclear Information System (INIS)

    Skinner, C.; Rais, B.; Roquemore, A.L.; Kugel, H.W.; Marsala, R.; Provost, T.

    2010-01-01

    The first real-time detection of surface dust inside a tokamak was made using an electrostatic dust detector. A fine grid of interlocking circuit traces was installed in the NSTX vessel and biased to 50 v. Impinging dust particles created a temporary short circuit and the resulting current pulse was recorded by counting electronics. The techniques used to increase the detector sensitivity by a factor of x10,000 to match NSTX dust levels while suppressing electrical pickup are presented. The results were validated by comparison to lab measurements, by the null signal from a covered detector that was only sensitive to pickup, and by the dramatic increase in signal when Li particles were introduced for wall conditioning purposes.

  2. The impact of the Pacific Decadal Oscillation on springtime dust activity in Syria

    Directory of Open Access Journals (Sweden)

    B. Pu

    2016-10-01

    Full Text Available The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as to whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific Decadal Oscillation (PDO on dust activities in Syria using an innovative dust optical depth (DOD dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003 to 2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near-surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabia to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa.On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria (associated with increased precipitation in Turkey and northern Syria is also critical for the development of strong springtime dust storms in Syria.

  3. The impact of Pacific Decadal Oscillation on springtime dust activity in Syria

    Science.gov (United States)

    Pu, B.; Ginoux, P. A.

    2016-12-01

    The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific decadal oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003-2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabian to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa. On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria associated with increased precipitation in Turkey and northern Syria is also critical for the development of strong springtime dust storms in Syria.

  4. The impact of the Pacific Decadal Oscillation on springtime dust activity in Syria

    Science.gov (United States)

    Pu, Bing; Ginoux, Paul

    2016-10-01

    The increasing trend of aerosol optical depth in the Middle East and a recent severe dust storm in Syria have raised questions as to whether dust storms will increase and promoted investigations on the dust activities driven by the natural climate variability underlying the ongoing human perturbations such as the Syrian civil war. This study examined the influences of the Pacific Decadal Oscillation (PDO) on dust activities in Syria using an innovative dust optical depth (DOD) dataset derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products. A significantly negative correlation is found between the Syrian DOD and the PDO in spring from 2003 to 2015. High DOD in spring is associated with lower geopotential height over the Middle East, Europe, and North Africa, accompanied by near-surface anomalous westerly winds over the Mediterranean basin and southerly winds over the eastern Arabian Peninsula. These large-scale patterns promote the formation of the cyclones over the Middle East to trigger dust storms and also facilitate the transport of dust from North Africa, Iraq, and Saudi Arabia to Syria, where the transported dust dominates the seasonal mean DOD in spring. A negative PDO not only creates circulation anomalies favorable to high DOD in Syria but also suppresses precipitation in dust source regions over the eastern and southern Arabian Peninsula and northeastern Africa.On the daily scale, in addition to the favorable large-scale condition associated with a negative PDO, enhanced atmospheric instability in Syria (associated with increased precipitation in Turkey and northern Syria) is also critical for the development of strong springtime dust storms in Syria.

  5. Detecting Exoplanets with the New Worlds Observer: The Problem of Exozodiacal Dust

    Science.gov (United States)

    Roberge, A.; Noecker, M. C.; Glassman, T. M.; Oakley, P.; Turnbull, M. C.

    2009-01-01

    Dust coming from asteroids and comets will strongly affect direct imaging and characterization of terrestrial planets in the Habitable Zones of nearby stars. Such dust in the Solar System is called the zodiacal dust (or 'zodi' for short). Higher levels of similar dust are seen around many nearby stars, confined in disks called debris disks. Future high-contrast images of an Earth-like exoplanet will very likely be background-limited by light scattered of both the local Solar System zodi and the circumstellar dust in the extrasolar system (the exozodiacal dust). Clumps in the exozodiacal dust, which are expected in planet-hosting systems, may also be a source of confusion. Here we discuss the problems associated with imaging an Earth-like planet in the presence of unknown levels of exozodiacal dust. Basic formulae for the exoplanet imaging exposure time as function of star, exoplanet, zodi, exozodi, and telescope parameters will be presented. To examine the behavior of these formulae, we apply them to the New Worlds Observer (NWO) mission. NWO is a proposed 4-meter UV/optical/near-IR telescope, with a free flying starshade to suppress the light from a nearby star and achieve the high contrast needed for detection and characterization of a terrestrial planet in the star's Habitable Zone. We find that NWO can accomplish its science goals even if exozodiacal dust levels are typically much higher than the Solar System zodi level. Finally, we highlight a few additional problems relating to exozodiacal dust that have yet to be solved.

  6. Grain dust and the lungs.

    Science.gov (United States)

    Chan-Yeung, M.; Ashley, M. J.; Grzybowski, S.

    1978-01-01

    Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler's lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust. Images p1272-a PMID:348288

  7. Charged dust structures in plasmas

    International Nuclear Information System (INIS)

    Cramer, N.F.; Vladimirov, S.V.

    1999-01-01

    We report here on theoretical investigations of the mechanical-electrostatic modes of vibration of a dust-plasma crystal, extending earlier work on the transverse modes of a horizontal line of grains (where the ions flow vertically downward to a plane horizontal cathode), the modes of two such lines of grains, and the modes of a vertical string of grains. The last two arrangements have the unique feature that the effect of the background plasma on the mutual grain interaction is asymmetric because of the wake downstream of the grains studied in. The characteristic frequencies of the vibrations are dependent on the parameters of the plasma and the dust grains, such as the Debye length and the grain charge, and so measurement of the frequencies could provide diagnostics of these quantities. Although the current boom in dusty plasma research is driven mainly by such industrial applications as plasma etching, sputtering and deposition, the physical outcomes of investigations in this rapidly expanding field cover many important topics in space physics and astrophysics as well. Examples are the interaction of dust with spacecraft, the structure of planetary rings, star formation, supernova explosions and shock waves. In addition, the study of the influence of dust in environmental research, such as in the Earth's ionosphere and atmosphere, is important. The unique binding of dust particles in a plasma opens possibilities for so-called super-chemistry, where the interacting bound elements are not atoms but dust grains

  8. Suspended dust in Norwegian cities

    International Nuclear Information System (INIS)

    2001-01-01

    According to calculations, at least 80 000 people in Oslo and 8 000 in Trondheim were annoyed by too much suspended dust in 2000. The dust concentration is greatest in the spring, presumably because dust is swirling up from melting snow and ice on the streets. Car traffic is the main source of the dust, except for some of the most highly exposed regions where wood-firing from old stoves contributes up to 70 percent of the dust. National targets for air quality include suspended dust, nitrogen dioxide, sulphur dioxide and benzene. Calculations show that nitrogen dioxide emissions exceeding the limit affected 4 000 people in Oslo and 1 000 people in Trondheim. The sulphur dioxide emissions in the major cities did non exceed the national quality limit; they did exceed the limit in some of the smaller industrial centres. In Trondheim, measurements show that the national limit for benzene was exceeded. Most of the emission of nitrogen dioxide comes from the road traffic. Local air pollution at times causes considerable health- and well-being problems in the larger cities and industrial centres, where a great part of the population may be at risk of early death, infection of the respiratory passage, heart- and lung diseases and cancer

  9. Preliminary analysis of hydrogen risk caused by dust in ITER

    International Nuclear Information System (INIS)

    Cheng Kun; Tong Lili; Cao Xuewu

    2012-01-01

    A lot of dust will be generated during ITER operation,and hydrogen will be produced by the interaction of hot dust with water in the case of coolant ingress accident. The accumulated hydrogen will bring risk of combustion and explosion,which will damage the device. CFD method has been used to analyze the produced hydrogen in 'wet bypass' scenario, and come to the results that hydrogen will burn and explode at the beginning of the accident, different hydrogen risk will be brought by different coolant leakage, and hydrogen risk will be inert if the leakage is massive.Injecting CO 2 to inert the vacuum vessel has also been discussed, the risk of hydrogen will be suppressed by injecting CO 2 with a large rate at the beginning of accident. (authors)

  10. Deconstructing continuous flash suppression.

    Science.gov (United States)

    Yang, Eunice; Blake, Randolph

    2012-03-08

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

  11. Study on treatment of dust by dismantling

    International Nuclear Information System (INIS)

    Torikai, K.; Suzuki, K.

    1987-01-01

    In dismantling of nuclear reactors, various kinds of treatment of dust generated by cutting or dismantling concrete structures of components of reactors are evaluated for safety, cost, and performance comparing the work in air with water. A method of dust treatment for work in air is discussed. The dry method has an easy operation in practice and a good performance in the equipment, but has problem on the prevention from radioactive contamination by diffusion of dust in air. For the purpose of advancing the strong points and eliminating the weak points in dry method, an improved venturi scrubber system is proposed for dismantling work as a dust collecting system. The system consists of dust absorbing pipe, dust collector, separator of dust and water and dust transfer equipment to a storage of waste. This system would be expected to have better performance and lower operating cost in decommissioning nuclear reactors, especially, the number of dust filters, for example, HEPA filters, will be considerably saved

  12. Four Interstellar Dust Candidates from the Stardust Interstellar Dust Collector

    Science.gov (United States)

    Westphal, A. J.; Allen, C.; Bajt, S.; Bechtel, H. A.; Borg, J.; Brenker, F.; Bridges, J.; Brownlee, D. E.; Burchell, M.; Burghammer, M.; hide

    2011-01-01

    In January 2006, the Stardust sample return capsule returned to Earth bearing the first solid samples from a primitive solar system body, Comet 81P/Wild2, and a collector dedicated to the capture and return of contemporary interstellar dust. Both collectors were approx. 0.1 sq m in area and were composed of aerogel tiles (85% of the collecting area) and aluminum foils. The Stardust Interstellar Dust Collector (SIDC) was exposed to the interstellar dust stream for a total exposure factor of 20 sq m/day. The Stardust Interstellar Preliminary Examination (ISPE) is a consortium-based project to characterize the collection using nondestructive techniques. The goals and restrictions of the ISPE are described . A summary of analytical techniques is described.

  13. Control of coal-dust in mines. Second edition. Bor'ba s ugol'noi i porodnoi pyl'yu v shakhtakh

    Energy Technology Data Exchange (ETDEWEB)

    Pemrukhin, P.M.; Grodel, G.S.; Zhilyaev, N.I.; Korenev, A.P.; Krivokhizha, B.M.; Kul' bachnyi, A.N.; Lyubimoba, A.I.; Medvedev, E.N.; Yaremachenko, P.P.

    1981-01-01

    An examination is made of problems concerned with over-all removal of dust from the air in mines. A description is given of physical and physico-chemical properties of ore mine dust that are of importance to evaluating processes in the formation, propagation and suppression of dust. Results are given for theoretical and on-site studies of dust aerodynamics in mines. A presentation is made of contemporary measures for controlling coal and rock dust in mines as well as means and methods of controlling air dust-level. Technical characteristics are given for new instruments for measuring air dust level. Brief data are given on preliminary wetting of coal in a massif, and a discussion is made of theoretical and practical problems related to hydro-dedusting, dust suppression, and dust removal during the operation of mining machinery as well as instruments for dedusting air on the surface complex of a mine. The book is intended for engineering-technical personnel in coal mines, design-planning and scientific-research institutes. 52 references, 61 tables.

  14. Cosmic dust investigations. Pt. 2

    International Nuclear Information System (INIS)

    Simpson, J.A.; Tuzzolino, A.J.

    1989-01-01

    A series of experiments have been completed using accelerator dust particles in the mass range ≅ 10 -9 -10 -6 g and velocity range ≅ 2-12 km/s to measure the velocity loss and degree of fragmentation for dust particles penetrating 6 and 28 μm thick polyvinylidene fluoride (PVDF) dust detectors. These measurements prove that even for a ratio of PVDF foil thickness to particle diameter as large as 0.6, the velocity loss and fragmentation is far less than expected from earlier reports in the literature. For 6 μm thick foils the velocity loss is ≤5%. These experiments are based on an extension of our earlier work which showed that two PVDF foils spaced a given distance apart could provide accurate time-of-flight (TOF) information due to the fast pulse rise time of PVDF detector response. We also report on our present state of development of PVDF position-sensing detectors which identify the x, y coordinates of particle impact, using detector and electronic pulse techniques adapted from our semiconductor position-sensing cosmic-ray detectors. Typical position errors of ≅ 1 mm are readily achieved. Finally, we have combined the above developments into a dust-particle telescope which accurately (≅ 1 0 angular accuracy) measures the trajectory of the incident particle as well as its mass and incident velocity, irrespective of whether it is a charged or neutral particle. We discuss how this practical dust telescope can be combined with dust capture cells for space flight and later recovery for laboratory determination of elemental and isotopic composition of captured dust. We also describe a simpler trajectory array based on discrete mosaics of thin detectors which would measure trajectories with a mean angular error of ≅ 4 0 . We discuss the application of these instruments for distinguishing between interplanetary dust of cometary and asteroidal origin, and for measurements on a space station, from near-Earth trapped dust of artificial origin. (orig.)

  15. Charged dust in saturn's magnetosphere

    International Nuclear Information System (INIS)

    Mendis, D.A.; Hill, J.R.; Houpis, H.L.F.

    1983-01-01

    Gravito-electrodynamic theory of charged dust grains is used to explain a variety of phenomena in those portions of the Saturnian ring system that are known to be dominated by fine (micron- and submicron-sized) dust, and in which collisional forces and Coulomb drag can be neglected. Among the phenomena discussed are the formation and evolution of the rotating near-radial spokes in the B-ring, the formation of waves in the F-ring, the cause of eccentricities of certain isolated ringlets, and the origin and morphology of the broad diffuse E-ring. Several novel processes predicted by the gravitoelectrodynamic theory, including 'magneto-gravitational capture' of exogenic dust by the magnetosphere, '1:1 magneto-gravitational orbital resonances' of charged dust with nearby satellites, and 'gyro-orbital resonances,' are used to explain individual observations. The effect of a ring current associated with this charged dust is also evaluated. Finally, the cosmogonic implications of the magneto-gravitational theory are briefly discussed. While several (although not all) of these processes have been discussed by one or more of the present authors elsewhere, the purpose of this paper is to synthesize all these processes within the framework of gravito-electrodynamics, and also to show its range of applicability within Saturn's ring system

  16. Spring Dust Storm Smothers Beijing

    Science.gov (United States)

    2002-01-01

    A few days earlier than usual, a large, dense plume of dust blew southward and eastward from the desert plains of Mongolia-quite smothering to the residents of Beijing. Citizens of northeastern China call this annual event the 'shachenbao,' or 'dust cloud tempest.' However, the tempest normally occurs during the spring time. The dust storm hit Beijing on Friday night, March 15, and began coating everything with a fine, pale brown layer of grit. The region is quite dry; a problem some believe has been exacerbated by decades of deforestation. According to Chinese government estimates, roughly 1 million tons of desert dust and sand blow into Beijing each year. This true-color image was made using two adjacent swaths (click to see the full image) of data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, on March 17, 2002. The massive dust storm (brownish pixels) can easily be distinguished from clouds (bright white pixels) as it blows across northern Japan and eastward toward the open Pacific Ocean. The black regions are gaps between SeaWiFS' viewing swaths and represent areas where no data were collected. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  17. Physical properties of five grain dust types.

    Science.gov (United States)

    Parnell, C B; Jones, D D; Rutherford, R D; Goforth, K J

    1986-01-01

    Physical properties of grain dust derived from five grain types (soybean, rice, corn, wheat, and sorghum) were measured and reported. The grain dusts were obtained from dust collection systems of terminal grain handling facilities and were assumed to be representative of grain dust generated during the handling process. The physical properties reported were as follows: particle size distributions and surface area measurements using a Coulter Counter Model TAII; percent dust fractions less than 100 micron of whole dust; bulk density; particle density; and ash content. PMID:3709482

  18. Glass Frit Clumping And Dusting

    International Nuclear Information System (INIS)

    Steimke, J. L.

    2013-01-01

    DWPF mixes a slurry of glass frit (Frit 418) and dilute (1.5 wt%) formic acid solution with high level waste in the Slurry Mix Evaporator (SME). There would be advantages to introducing the frit in a non-slurry form to minimize water addition to the SME, however, adding completely dry frit has the potential to generate dust which could clog filters or condensers. Prior testing with another type of frit, Frit 320, and using a minimal amount of water reduced dust generation, however, the formation of hard clumps was observed. To examine options and behavior, a TTQAP [McCabe and Stone, 2013] was written to initiate tests that would address these concerns. Tests were conducted with four types of glass frit; Frit 320, DWPF Frit 418, Bekeson Frit 418 and Multi-Aspirator Frit 418. The last two frits are chemically identical to DWPF Frit 418 but smaller particles were removed by the respective vendors. Test results on Frit Clumping and Dusting are provided in this report. This report addresses the following seven questions. Short answers are provided below with more detailed answers to follow. 1. Will the addition of a small amount of water, 1.5 wt%, to dry DWPF Frit 418 greatly reduce the dust generation during handling at DWPF? a. Yes, a small scale test showed that adding a little water to the frit greatly reduced dust generation during handling. 2. Will the addition of small amounts of water to the frit cause clumping that will impair frit handling at DWPF? a. No, not with Frit 418. Although clumps were observed to form when 1.5 wt% water was mixed with DWPF Frit 418, then compressed and air-dried overnight, the clumps were easily crushed and did not form the hardened material noted when Frit 320 was tested. 3. What is the measured size distribution of dust generated when dry frit is handled? (This affects the feasibility and choice of processing equipment for removing the dust generating fraction of the frit before it is added to the SME.) a. The size distribution for

  19. Glass Frit Clumping And Dusting

    Energy Technology Data Exchange (ETDEWEB)

    Steimke, J. L.

    2013-09-26

    DWPF mixes a slurry of glass frit (Frit 418) and dilute (1.5 wt%) formic acid solution with high level waste in the Slurry Mix Evaporator (SME). There would be advantages to introducing the frit in a non-slurry form to minimize water addition to the SME, however, adding completely dry frit has the potential to generate dust which could clog filters or condensers. Prior testing with another type of frit, Frit 320, and using a minimal amount of water reduced dust generation, however, the formation of hard clumps was observed. To examine options and behavior, a TTQAP [McCabe and Stone, 2013] was written to initiate tests that would address these concerns. Tests were conducted with four types of glass frit; Frit 320, DWPF Frit 418, Bekeson Frit 418 and Multi-Aspirator Frit 418. The last two frits are chemically identical to DWPF Frit 418 but smaller particles were removed by the respective vendors. Test results on Frit Clumping and Dusting are provided in this report. This report addresses the following seven questions. Short answers are provided below with more detailed answers to follow. 1. Will the addition of a small amount of water, 1.5 wt%, to dry DWPF Frit 418 greatly reduce the dust generation during handling at DWPF? a. Yes, a small scale test showed that adding a little water to the frit greatly reduced dust generation during handling. 2. Will the addition of small amounts of water to the frit cause clumping that will impair frit handling at DWPF? a. No, not with Frit 418. Although clumps were observed to form when 1.5 wt% water was mixed with DWPF Frit 418, then compressed and air-dried overnight, the clumps were easily crushed and did not form the hardened material noted when Frit 320 was tested. 3. What is the measured size distribution of dust generated when dry frit is handled? (This affects the feasibility and choice of processing equipment for removing the dust generating fraction of the frit before it is added to the SME.) a. The size distribution for

  20. Dust deposit in recirculation regions

    International Nuclear Information System (INIS)

    Griemert, R.

    1985-03-01

    The present report shows investigations, which have been carried out in a closed duct at forward and backward facing steps. Distribution of fluid velocity and fluid fluctuations in and normal to main flow direction as well as the distribution of Reynolds shear stress have been measured. The mass transfer downstream of a backward facing step has been investigated as well. By using graphite-, copper-, tin- and rubber dust, conditions of deposition have been defined experimentally. A serie of photos shows the filling of a recirculation region downstream of a backward facing step with graphite dust. The present investigations allow to avoid deposition of dust in recirculation regions by selecting the fluid numbers in an appropriate way. (orig.) [de

  1. Dust Storm Hits Canary Islands

    Science.gov (United States)

    2002-01-01

    A thick pall of sand and dust blew out from the Sahara Desert over the Atlantic Ocean yesterday (January 6, 2002), engulfing the Canary Islands in what has become one of the worst sand storms ever recorded there. In this scene, notice how the dust appears particularly thick in the downwind wake of Tenerife, the largest of the Canary Islands. Perhaps the turbulence generated by the air currents flowing past the island's volcanic peaks is churning the dust back up into the atmosphere, rather than allowing it to settle toward the surface. This true-color image was captured by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on January 7, 2002. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  2. Mechanisms of metal dusting corrosion

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo

    In this thesis the early stages of metal dusting corrosion is addressed; the development of carbon expanded austenite, C, and the decomposition hereof into carbides. Later stages of metal dusting corrosion are explored by a systematic study of stainless steel foils exposed to metal dusting...... deformed stainless steel flakes is transformed to expanded martensite/austenite during low-temperature carburization. Various experimental procedures to experimentally determine the concentration dependent diffusion coefficient of carbon in expanded austenite are evaluated. The most promising procedure...... powders and flakes. The nature of the decomposition products, carbides of the form M23C6 and M7C3, were evaluated by X-ray diffraction, light optical microscopy, scanning electron microscopy and thermodynamic modelling. The decomposition was found to be dependent on several parameters such as thermal...

  3. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile δ13CH4 analysis

    Science.gov (United States)

    Rella, C.; Crosson, E.; Petron, G.; Sweeney, C.; Karion, A.

    2013-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the δ13CH4 signature to distinguish between natural gas and landfills or ruminants. We present measurements of mobile field δ13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to arrive at an overall isotope ratio for the region. (left panel) Distribution of oil and gas well pads (yellow) and landfills (blue) in the Dallas / Ft. Worth area. Mobile nocturnal measurements

  4. Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Weld County Colorado using δ13CH4 analysis

    Science.gov (United States)

    Rella, C.; Jacobson, G. A.; Crosson, E.; Sweeney, C.; Karion, A.; Petron, G.

    2012-12-01

    Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Given that the global warming potential of methane is many times greater than that of carbon dioxide (Forster et al. 2007), the importance of quantifying methane emissions becomes clear. Companion presentations at this meeting describe efforts to quantify the overall methane emissions in two separate gas producing areas in Colorado and Utah during intensive field campaigns undertaken in 2012. A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One method for assessing the contribution of these different sources is stable isotope analysis. In particular, the δ13CH4 signature of natural gas (-37 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-50 to -70 permil). In this paper we present measurements of δ13CH4 in Colorado in Weld County, a region of intense natural gas production, using a mobile δ13CH4¬ analyzer capable of high-precision measurements of the stable isotope ratio of methane at ambient levels. This analyzer was used to make stable isotope measurements at a fixed location near the center of the gas producing region, from which an overall isotope ratio for the regional emissions is determined. In addition, mobile measurements in the nocturnal boundary layer have been made, over a total distance of 150 km throughout Weld County, allowing spatially resolved measurements of this isotope signature. Finally, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in this region, by making

  5. The effect of organic coating on the heterogeneous ice nucleation efficiency of mineral dust aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Moehler, O; Benz, S; Saathoff, H; Schnaiter, M; Wagner, R [Forschungszentrum Karlsruhe, Institute for Meteorology and Climate Research, 76021 Karlsruhe (Germany); Schneider, J; Walter, S [Max Planck Institute for Chemistry, 55128 Mainz (Germany); Ebert, V; Wagner, S [University of Heidelberg, Institute for Physical Chemistry, 69120 Heidelberg (Germany)], E-mail: Ottmar.Moehler@imk.fzk.de

    2008-04-15

    The effect of organic coating on the heterogeneous ice nucleation (IN) efficiency of dust particles was investigated at simulated cirrus cloud conditions in the AIDA cloud chamber of Forschungszentrum Karlsruhe. Arizona test dust (ATD) and the clay mineral illite were used as surrogates for atmospheric dust aerosols. The dry dust samples were dispersed into a 3.7 m{sup 3} aerosol vessel and either directly transferred into the 84 m{sup 3} cloud simulation chamber or coated before with the semi-volatile products from the reaction of {alpha}-pinene with ozone in order to mimic the coating of atmospheric dust particles with secondary organic aerosol (SOA) substances. The ice-active fraction was measured in AIDA expansion cooling experiments as a function of the relative humidity with respect to ice, RHi, in the temperature range from 205 to 210 K. Almost all uncoated dust particles with diameters between 0.1 and 1.0 {mu}m acted as efficient deposition mode ice nuclei at RHi between 105 and 120%. This high ice nucleation efficiency was markedly suppressed by coating with SOA. About 20% of the ATD particles coated with a SOA mass fraction of 17 wt% were ice-active at RHi between 115 and 130%, and only 10% of the illite particles coated with an SOA mass fraction of 41 wt% were ice-active at RHi between 160 and 170%. Only a minor fraction of pure SOA particles were ice-active at RHi between 150 and 190%. Strong IN activation of SOA particles was observed only at RHi above 200%, which is clearly above water saturation at the given temperature. The IN suppression and the shift of the heterogeneous IN onset to higher RHi seem to depend on the coating thickness or the fractional surface coverage of the mineral particles. The results indicate that the heterogeneous ice nucleation potential of atmospheric mineral particles may also be suppressed if they are coated with secondary organics.

  6. The effect of organic coating on the heterogeneous ice nucleation efficiency of mineral dust aerosols

    International Nuclear Information System (INIS)

    Moehler, O; Benz, S; Saathoff, H; Schnaiter, M; Wagner, R; Schneider, J; Walter, S; Ebert, V; Wagner, S

    2008-01-01

    The effect of organic coating on the heterogeneous ice nucleation (IN) efficiency of dust particles was investigated at simulated cirrus cloud conditions in the AIDA cloud chamber of Forschungszentrum Karlsruhe. Arizona test dust (ATD) and the clay mineral illite were used as surrogates for atmospheric dust aerosols. The dry dust samples were dispersed into a 3.7 m 3 aerosol vessel and either directly transferred into the 84 m 3 cloud simulation chamber or coated before with the semi-volatile products from the reaction of α-pinene with ozone in order to mimic the coating of atmospheric dust particles with secondary organic aerosol (SOA) substances. The ice-active fraction was measured in AIDA expansion cooling experiments as a function of the relative humidity with respect to ice, RHi, in the temperature range from 205 to 210 K. Almost all uncoated dust particles with diameters between 0.1 and 1.0 μm acted as efficient deposition mode ice nuclei at RHi between 105 and 120%. This high ice nucleation efficiency was markedly suppressed by coating with SOA. About 20% of the ATD particles coated with a SOA mass fraction of 17 wt% were ice-active at RHi between 115 and 130%, and only 10% of the illite particles coated with an SOA mass fraction of 41 wt% were ice-active at RHi between 160 and 170%. Only a minor fraction of pure SOA particles were ice-active at RHi between 150 and 190%. Strong IN activation of SOA particles was observed only at RHi above 200%, which is clearly above water saturation at the given temperature. The IN suppression and the shift of the heterogeneous IN onset to higher RHi seem to depend on the coating thickness or the fractional surface coverage of the mineral particles. The results indicate that the heterogeneous ice nucleation potential of atmospheric mineral particles may also be suppressed if they are coated with secondary organics

  7. Intergalactic dust and quasar distribution

    International Nuclear Information System (INIS)

    Soltan, A.

    1979-01-01

    Non-homogeneous intergalactic extinction may considerably affect the quasar distribution. Especially samples of quasars isolated on the basis of B-V colours are subject to this phenomenon. Apparent grouping and close pairs of quasars reported in the literature may be a result of intergalactic dust. Using surface distribution of faint blue objects selected by Hawkins and Reddish it is estimated that intergalactic extinction in B should reach approximately 1 mag out to the redshift of approximately 1. This is slightly larger than predicted by theory and comparable to the mean dust density derived from observations. (Author)

  8. The distribution of interstellar dust

    International Nuclear Information System (INIS)

    Clocchiatti, A.; Marraco, H.G.

    1986-01-01

    We propose the interstellar matter structural function as a tool to derive the features of the interstellar dust distribution. We study that function resolving some ideal dust distribution models. Later we describe the method used to find a reliable computing algorithm for the observational case. Finally, we describe the steps to build a model for the interstellar matter composed by spherically symmetrical clouds. The density distribution for each of these clouds is D(r) = D 0 .esup(-r/r 0 ) 2 . The preliminary results obtained are summarised. (author)

  9. Electrostatic Dust Detector with Improved Sensitivity

    International Nuclear Information System (INIS)

    Boyle, D.P.; Skinner, C.H.; Roquemore, A.L.

    2008-01-01

    Methods to measure the inventory of dust particles and to remove dust if it approaches safety limits will be required in next-step tokamaks such as ITER. An electrostatic dust detector, based on a fine grid of interlocking circuit traces, biased to 30 or 50 V, has been developed for the detection of dust on remote surfaces in air and vacuum environments. Gaining operational experience of dust detection on surfaces in tokamaks is important, however the level of dust generated in contemporary short-pulse tokamaks is comparatively low and high sensitivity is necessary to measure dust on a shot-by-shot basis. We report on modifications in the detection electronics that have increased the sensitivity of the electrostatic dust detector by a factor of up to 120, - a level suitable for measurements on contemporary tokamaks.

  10. Infrared Observations of Cometary Dust and Nuclei

    Science.gov (United States)

    Lisse, Carey

    2004-01-01

    This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.

  11. The global distribution of mineral dust

    International Nuclear Information System (INIS)

    Tegen, I; Schepanski, K

    2009-01-01

    Dust aerosol particles produced by wind erosion in arid and semi arid regions affect climate and air quality, but the magnitude of these effects is largely unquantified. The major dust source regions include the Sahara, the Arabian and Asian deserts; global annual dust emissions are currently estimated to range between 1000 and 3000 Mt/yr. Dust aerosol can be transported over long distances of thousands of kilometers, e.g. from source regions in the Saharan desert over the North Atlantic, or from the Asian deserts towards the Pacific Ocean. The atmospheric dust load varies considerably on different timescales. While dust aerosol distribution and dust effects are important on global scales, they strongly depend on dust emissions that are controlled on small spatial and temporal scales.

  12. Exact solutions for rotating charged dust

    International Nuclear Information System (INIS)

    Islam, J.N.

    1984-01-01

    Earlier work by the author on rotating charged dust is summarized. An incomplete class of exact solutions for differentially rotating charged dust in Newton-Maxwell theory for the equal mass and charge case that was found earlier is completed. A new global exact solution for cylindrically symmetric differentially rotating charged dust in Newton-Maxwell theory is presented. Lastly, a new exact solution for cylindrically symmetric rigidly rotating charged dust in general relativity is given. (author)

  13. Studies of dust shells around stars

    International Nuclear Information System (INIS)

    Bedijn, P.J.

    1977-01-01

    This thesis deals with some aspects of circumstellar dust shells. This dust shell, emitting infrared radiation, is described by way of its absorptive and emissive properties as well as by the transfer of radiation through the dust shell itself. Model calculations are compared to experimental results and agree reasonably well. The author also discusses the dynamics of the extended shells of gas and dust around newly formed stars

  14. Sodium fire suppression

    Energy Technology Data Exchange (ETDEWEB)

    Malet, J C [DSN/SESTR, Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1979-03-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  15. Sodium fire suppression

    International Nuclear Information System (INIS)

    Malet, J.C.

    1979-01-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  16. An evaluation of traditional and emerging remote sensing technologies for the detection of fugitive contamination at selected Superfund hazardous waste sites

    Science.gov (United States)

    Slonecker, E. Terrence; Fisher, Gary B.

    2011-01-01

    This report represents a remote sensing research effort conducted by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency (EPA) for the EPA Office of Inspector General. The objective of this investigation was to explore the efficacy of remote sensing as a technology for postclosure monitoring of hazardous waste sites as defined under the Comprehensive Environmental Response Compensation and Liability Act of 1980 (Public Law 96-510, 42 U.S.C. §9601 et seq.), also known as \\"Superfund.\\" Five delisted Superfund sites in Maryland and Virginia were imaged with a hyperspectral sensor and visited for collection of soil, water, and spectral samples and inspection of general site conditions. This report evaluates traditional and hyperspectral imagery and field spectroscopic measurement techniques in the characterization and analysis of fugitive (anthropogenic, uncontrolled) contamination at previously remediated hazardous waste disposal sites.

  17. Radio frequency discharge with dust particles

    NARCIS (Netherlands)

    Chutov, Y. I.; W. J. Goedheer,; Kravchenko, O. Y.; Zuz, V. M.; Yan, M.; Martins, R.; Ferreira, I.; Fortunato, E.; Kroesen, G.

    2000-01-01

    A 1D PIC/MCC method has been developed for computer simulations of low-pressure RF discharges with dust particles using the method for dust-free discharges. A RF discharge in argon with dust particles distributed uniformly in the interelectrode gap is simulated at parameters providing a possibility

  18. Thirteen years of Aeolian dust dynamics in a desert region (Negev desert, Israel): analysis of horizontal and vertical dust flux, vertical dust distribution and dust grain size

    NARCIS (Netherlands)

    Offer, Z.Y.; Goossens, D.

    2004-01-01

    At Sede Boqer (northern Negev desert, Israel), aeolian dust dynamics have been measured during the period 1988–2000. This study focuses on temporal records of the vertical and horizontal dust flux, the vertical distribution of the dust particles in the atmosphere, and the grain size of the

  19. Dust Measurements Onboard the Deep Space Gateway

    Science.gov (United States)

    Horanyi, M.; Kempf, S.; Malaspina, D.; Poppe, A.; Srama, R.; Sternovsky, Z.; Szalay, J.

    2018-02-01

    A dust instrument onboard the Deep Space Gateway will revolutionize our understanding of the dust environment at 1 AU, help our understanding of the evolution of the solar system, and improve dust hazard models for the safety of crewed and robotic missions.

  20. Properties of interstellar dust in reflection nebulae

    International Nuclear Information System (INIS)

    Sellgren, K.

    1988-01-01

    Observations of interstellar dust in reflection nebulae are the closest analog in the interstellar medium to studies of cometary dust in our solar system. The presence of a bright star near the reflection nebula dust provides the opportunity to study both the reflection and emission characteristics of interstellar dust. At 0.1 to 1 micrometer, the reflection nebula emission is due to starlight scattered by dust. The albedo and scattering phase function of the dust is determined from observations of the scattered light. At 50 to 200 micrometers, thermal emission from the dust in equilibrium with the stellar radiation field is observed. The derived dust temperature determines the relative values of the absorption coefficient of the dust at wavelengths where the stellar energy is absorbed and at far infrared wavelengths where the absorbed energy is reradiated. These emission mechanisms directly relate to those seen in the near and mid infrared spectra of comets. In a reflection nebula the dust is observed at much larger distances from the star than in our solar system, so that the equilibrium dust temperature is 50 K rather than 300 K. Thus, in reflection nebulae, thermal emission from dust is emitted at 50 to 200 micrometer

  1. House dust extracts contain potent immunological adjuvants

    NARCIS (Netherlands)

    Beukelman, C.J.; Dijk, H. van; Aerts, P.C.; Rademaker, P.M.; Berrens, L.; Willers, J.M.N.

    1987-01-01

    A crude aqueous extract of house dust and two house dust subfractions were tested for adjuvant activity in a sensitivity assay performed in mice. Evidence is presented that house dust contains at least two potent immunological adjuvants. One of these, present in both subfractions, was probably

  2. Observed spectral features of dust

    International Nuclear Information System (INIS)

    Willner, S.P.

    1984-01-01

    The author concentrates on the observed properties of dust spectral features. Identifications, based on laboratory data, are given whenever plausible ones exist. There are a very large number of papers in the literature of even such a young field as infrared spectroscopy, and therefore the author refers only to the most recent paper on a topic or to another review. (Auth.)

  3. Meteors, meteorites and cosmic dust

    International Nuclear Information System (INIS)

    Lebedinets, V.N.

    1987-01-01

    The problem of meteorite origin and meteorite composition is discussed. Nowadays, most scientists suppose that the giant Oort cloud consisting of ice comet nuclei is the sourse of the meteor matter. A principle unity of the matter of meteorites falling to the Earth and cosmic dust is noted as well as that of meteorite bodies evaporating in the atmosphere and bearing meteors and bodies

  4. Occupational diseases of dust etiology

    International Nuclear Information System (INIS)

    Sokolik, L.I.; Shkondin, A.N.

    1981-01-01

    Detailed etiologic and clinico-roentgenological characteristics of pneumoconiosis, as widely spread occupational disease caused by different kinds of dust, are given. The course of pneumoconiosis is discussed depending on working conditions of patients after the disease had been ascertained, as well as its complications, taking into account roentgeno-morphological types of fibrosis and the stages of the disease [ru

  5. 75 FR 32142 - Combustible Dust

    Science.gov (United States)

    2010-06-07

    .... Contact Mat Chibbaro, P.E., Fire Protection Engineer, Office of Safety Systems, OSHA Directorate of..., and metals (such as aluminum and magnesium). Industries that may have combustible dust hazards include..., chemical manufacturing, textile manufacturing, furniture manufacturing, metal processing, fabricated metal...

  6. Trapping Dust to Form Planets

    Science.gov (United States)

    Kohler, Susanna

    2017-10-01

    Growing a planet from a dust grain is hard work! A new study explores how vortices in protoplanetary disks can assist this process.When Dust Growth FailsTop: ALMA image of the protoplanetary disk of V1247 Orionis, with different emission components labeled. Bottom: Synthetic image constructed from the best-fit model. [Kraus et al. 2017]Gradual accretion onto a seed particle seems like a reasonable way to grow a planet from a grain of dust; after all, planetary embryos orbit within dusty protoplanetary disks, which provides them with plenty of fuel to accrete so they can grow. Theres a challenge to this picture, though: the radial drift problem.The radial drift problem acknowledges that, as growing dust grains orbit within the disk, the drag force on them continues to grow as well. For large enough dust grains perhaps around 1 millimeter the drag force will cause the grains orbits to decay, and the particles drift into the star before they are able to grow into planetesimals and planets.A Close-Up Look with ALMASo how do we overcome the radial drift problem in order to form planets? A commonly proposed mechanism is dust trapping, in which long-lived vortices in the disk trap the dust particles, preventing them from falling inwards. This allows the particles to persist for millions of years long enough to grow beyond the radial drift barrier.Observationally, these dust-trapping vortices should have signatures: we would expect to see, at millimeter wavelengths, specific bright, asymmetric structures where the trapping occurs in protoplanetary disks. Such disk structures have been difficult to spot with past instrumentation, but the Atacama Large Millimeter/submillimeter Array (ALMA) has made some new observations of the disk V1247 Orionis that might be just what were looking for.Schematic of the authors model for the disk of V1247 Orionis. [Kraus et al. 2017]Trapped in a Vortex?ALMAs observations of V1247 Orionis are reported by a team of scientists led by Stefan

  7. Cosmological simulation with dust formation and destruction

    Science.gov (United States)

    Aoyama, Shohei; Hou, Kuan-Chou; Hirashita, Hiroyuki; Nagamine, Kentaro; Shimizu, Ikkoh

    2018-06-01

    To investigate the evolution of dust in a cosmological volume, we perform hydrodynamic simulations, in which the enrichment of metals and dust is treated self-consistently with star formation and stellar feedback. We consider dust evolution driven by dust production in stellar ejecta, dust destruction by sputtering, grain growth by accretion and coagulation, and grain disruption by shattering, and treat small and large grains separately to trace the grain size distribution. After confirming that our model nicely reproduces the observed relation between dust-to-gas ratio and metallicity for nearby galaxies, we concentrate on the dust abundance over the cosmological volume in this paper. The comoving dust mass density has a peak at redshift z ˜ 1-2, coincident with the observationally suggested dustiest epoch in the Universe. In the local Universe, roughly 10 per cent of the dust is contained in the intergalactic medium (IGM), where only 1/3-1/4 of the dust survives against dust destruction by sputtering. We also show that the dust mass function is roughly reproduced at ≲ 108 M⊙, while the massive end still has a discrepancy, which indicates the necessity of stronger feedback in massive galaxies. In addition, our model broadly reproduces the observed radial profile of dust surface density in the circum-galactic medium (CGM). While our model satisfies the observational constraints for the dust extinction on cosmological scales, it predicts that the dust in the CGM and IGM is dominated by large (>0.03 μm) grains, which is in tension with the steep reddening curves observed in the CGM.

  8. Respiratory Toxicity of Lunar Highland Dust

    Science.gov (United States)

    James, John T.; Lam, Chiu-wing; Wallace, William T.

    2009-01-01

    Lunar dust exposures occurred during the Apollo missions while the crew was on the lunar surface and especially when microgravity conditions were attained during rendezvous in lunar orbit. Crews reported that the dust was irritating to the eyes and in some cases respiratory symptoms were elicited. NASA s vision for lunar exploration includes stays of 6 months on the lunar surface hence the health effects of periodic exposure to lunar dust need to be assessed. NASA has performed this assessment with a series of in vitro and in vivo tests on authentic lunar dust. Our approach is to "calibrate" the intrinsic toxicity of lunar dust by comparison to a nontoxic dust (TiO2) and a highly toxic dust (quartz) using intratrachael instillation of the dusts in mice. A battery of indices of toxicity is assessed at various time points after the instillations. Cultures of selected cells are exposed to test dusts to assess the adverse effects on the cells. Finally, chemical systems are used to assess the nature of the reactivity of various dusts and to determine the persistence of reactivity under various environmental conditions that are relevant to a space habitat. Similar systems are used to assess the dissolution of the dust. From these studies we will be able to set a defensible inhalation exposure standard for aged dust and predict whether we need a separate standard for reactive dust. Presently-available data suggest that aged lunar highland dust is slightly toxic, that it can adversely affect cultured cells, and that the surface reactivity induced by grinding the dust persists for a few hours after activation.

  9. Design and development of a dust dispersion chamber to quantify the dispersibility of rock dust.

    Science.gov (United States)

    Perera, Inoka E; Sapko, Michael J; Harris, Marcia L; Zlochower, Isaac A; Weiss, Eric S

    2016-01-01

    Dispersible rock dust must be applied to the surfaces of entries in underground coal mines in order to inert the coal dust entrained or made airborne during an explosion and prevent propagating explosions. 30 CFR. 75.2 states that "… [rock dust particles] when wetted and dried will not cohere to form a cake which will not be dispersed into separate particles by a light blast of air …" However, a proper definition or quantification of "light blast of air" is not provided. The National Institute for Occupational Safety and Health (NIOSH) has, consequently, designed a dust dispersion chamber to conduct quantitative laboratory-scale dispersibility experiments as a screening tool for candidate rock dusts. A reproducible pulse of air is injected into the chamber and across a shallow tray of rock dust. The dust dispersed and carried downwind is monitored. The mass loss of the dust tray and the airborne dust measurements determine the relative dispersibility of the dust with respect to a Reference rock dust. This report describes the design and the methodology to evaluate the relative dispersibility of rock dusts with and without anti-caking agents. Further, the results of this study indicate that the dispersibility of rock dusts varies with particle size, type of anti-caking agent used, and with the untapped bulk density. Untreated rock dusts, when wetted and dried forming a cake that was much less dispersible than the reference rock dust used in supporting the 80% total incombustible content rule.

  10. Dust bands in the asteroid belt

    International Nuclear Information System (INIS)

    Sykes, M.V.; Greenberg, R.; Dermott, S.F.; Nicholson, P.D.; Burns, J.A.

    1989-01-01

    This paper describes the original IRAS observations leading to the discovery of the three dust bands in the asteroid belt and the analysis of data. Special attention is given to an analytical model of the dust band torus and to theories concerning the origin of the dust bands, with special attention given to the collisional equilibrium (asteroid family), the nonequilibrium (random collision), and the comet hypotheses of dust-band origin. It is noted that neither the equilibrium nor nonequilibrium models, as currently formulated, present a complete picture of the IRAS dust-band observations. 32 refs

  11. Linear Alkylbenzenesulfonates in indoor Floor Dust

    DEFF Research Database (Denmark)

    Madsen, Jørgen Øgaard; Wolkoff, Peder; Madsen, Jørgen Øgaard

    1999-01-01

    The amount of Linear Alkylbenzenesulfonates (LAS) in the particle fraction of floor dust sampled from 7 selected public buildings varied between 34 and 1500 microgram per gram dust, while the contents of the fibre fractions generally were higher with up to 3500 microgram LAS/g dust. The use...... of a cleaning agent with LAS resulted in an increase of the amount of LAS in the floor dust after floor wash relative to just before floor wash. However, the most important source of LAS in the indoor floor dust appears to be residues of detergent in clothing. Thus, a newly washed shirt contained 2960 microgram...

  12. Time-Dependent Dust Formation in Novae

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    1991-06-01

    Full Text Available The dust formation processes in novae are investigated with close attention to recent infrared observations. Using mainly the classical nucleation theory, we have calculated the time scales of dust formation and growth in the environments of novae. Those time scales roughly resemble the typical observations. We have classified the dust-forming novae into three classes according to their explosion properties and the thermodynamic properties of dust grains. Oxygen grains from much later than carbon grains because of their thermodynamic properties. The effect of grain formation to the efficiency of stellar winds to drive the material outward is tested with newly obtained Planck mean values of dust grains.

  13. Numerical Prediction of Dust. Chapter 10

    Science.gov (United States)

    Benedetti, Angela; Baldasano, J. M.; Basart, S.; Benincasa, F.; Boucher, O.; Brooks, M.; Chen, J. P.; Colarco, P. R.; Gong, S.; Huneeus, N.; hide

    2013-01-01

    Covers the whole breadth of mineral dust research, from a scientific perspective Presents interdisciplinary work including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies Explores the role of dust as a player and recorder of environmental change This volume presents state-of-the-art research about mineral dust, including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies. Dust research is a new, dynamic and fast-growing area of science and due to its multiple roles in the Earth system, dust has become a fascinating topic for many scientific disciplines. Aspects of dust research covered in this book reach from timescales of minutes (as with dust devils, cloud processes, and radiation) to millennia (as with loess formation and oceanic sediments), making dust both a player and recorder of environmental change. The book is structured in four main parts that explore characteristics of dust, the global dust cycle, impacts of dust on the Earth system, and dust as a climate indicator. The chapters in these parts provide a comprehensive, detailed overview of this highly interdisciplinary subject. The contributions presented here cover dust from source to sink and describe all the processes dust particles undergo while travelling through the atmosphere. Chapters explore how dust is lifted and transported, how it affects radiation, clouds, regional circulations, precipitation and chemical processes in the atmosphere, and how it deteriorates air quality. The book explores how dust is removed from the atmosphere by gravitational settling, turbulence or precipitation, how iron contained in dust fertilizes terrestrial and marine ecosystems, and about the role that dust plays in human health. We learn how dust is observed, simulated using computer models and forecast. The book also details the role of dust deposits for climate reconstructions

  14. Dust removal system for fusion experimental reactors

    International Nuclear Information System (INIS)

    Onozuka, M.; Ueda, Y.; Takahashi, K.; Oda, Y.; Seki, Y.; Ueda, S.; Aoki, I.

    1995-01-01

    Development of a dust removal system using static electricity has been conducted. It is envisioned that the system can collect and transport dust under vacuum. In the system, the dust is charged by dielectric polarization and floated by an electrostatic attraction force that is generated by the DC electric field. The dust is then transported by the electric curtain formed by the three-phase AC electric field. Experimental investigation has been conducted to examine the characteristics of the system. Current research results indicate that the dust removal system using static electricity can be used for fusion experimental reactors

  15. Dust removal system for fusion experimental reactors

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, M.; Ueda, Y.; Takahashi, K.; Oda, Y. [Mitsubishi Heavy Industries, Ltd., Yokohama (Japan); Seki, Y.; Ueda, S.; Aoki, I. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan)

    1995-12-31

    Development of a dust removal system using static electricity has been conducted. It is envisioned that the system can collect and transport dust under vacuum. In the system, the dust is charged by dielectric polarization and floated by an electrostatic attraction force that is generated by the DC electric field. The dust is then transported by the electric curtain formed by the three-phase AC electric field. Experimental investigation has been conducted to examine the characteristics of the system. Current research results indicate that the dust removal system using static electricity can be used for fusion experimental reactors.

  16. ORIGIN OF DUST AROUND V1309 SCO

    International Nuclear Information System (INIS)

    Zhu, Chunhua; Lü, Guoliang; Wang, Zhaojun

    2013-01-01

    The origin of dust grains in the interstellar medium is still an unanswered problem. Nicholls et al. found the presence of a significant amount of dust around V1309 Sco, which may originate from the merger of a contact binary. We investigate the origin of dust around V1309 Sco and suggest that these dust grains are produced in the binary-merger ejecta. By means of the AGBDUST code, we estimate that ∼5.2 × 10 –4 M ☉ dust grains are produced with a radii of ∼10 –5 cm. These dust grains are mainly composed of silicate and iron grains. Because the mass of the binary merger ejecta is very small, the contribution of dust produced by binary merger ejecta to the overall dust production in the interstellar medium is negligible. However, it is important to note that the discovery of a significant amount of dust around V1309 Sco offers a direct support for the idea that common-envelope ejecta provides an ideal environment for dust formation and growth. Therefore, we confirm that common envelope ejecta can be important source of cosmic dust

  17. Response of the Water Cycle of West Africa and Atlantic to Radiative Forcing by Saharan Dust

    Science.gov (United States)

    Lau, K. M.; Kim, Kyu-Myong; Sud, Yogesh C.; Walker, Gregory L.

    2010-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence in support of the "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feed back triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Easter Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean. region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while long wave has the opposite response. The elevated dust layer warms the air over Nest Africa and the eastern Atlantic. The condensation heating associated with the induced deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface energy fluxes, resulting in cooling of the Nest African land and the eastern Atlantic, and a warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

  18. COSMIC DUST AGGREGATION WITH STOCHASTIC CHARGING

    International Nuclear Information System (INIS)

    Matthews, Lorin S.; Hyde, Truell W.; Shotorban, Babak

    2013-01-01

    The coagulation of cosmic dust grains is a fundamental process which takes place in astrophysical environments, such as presolar nebulae and circumstellar and protoplanetary disks. Cosmic dust grains can become charged through interaction with their plasma environment or other processes, and the resultant electrostatic force between dust grains can strongly affect their coagulation rate. Since ions and electrons are collected on the surface of the dust grain at random time intervals, the electrical charge of a dust grain experiences stochastic fluctuations. In this study, a set of stochastic differential equations is developed to model these fluctuations over the surface of an irregularly shaped aggregate. Then, employing the data produced, the influence of the charge fluctuations on the coagulation process and the physical characteristics of the aggregates formed is examined. It is shown that dust with small charges (due to the small size of the dust grains or a tenuous plasma environment) is affected most strongly

  19. Enhanced Saharan dust input to the Levant during Heinrich stadials

    Science.gov (United States)

    Torfstein, Adi; Goldstein, Steven L.; Stein, Mordechai

    2018-04-01

    The history of dust transport to the Levant during the last glacial period is reconstructed using the isotope ratios of Pb, Sr, Nd, and Hf in sediments of Lake Lisan, the last glacial Dead Sea. Exposed marginal sections of the Lisan Formation were sampled near Masada, the Perazim Valley and from a core drilled at the deep floor of the modern lake. Bulk samples and size fractions display unique isotopic fingerprints: the finest detritus fraction (<5 μm) displays higher 87Sr/86Sr and lower εNd values (0.710-0.713 and -7.0 to -9.8, respectively) relative to the coarser fractions (5-20 μm and <20 μm; 0.708-0.710 and -3.4 to -8.3) and the bulk detritus samples (0.709-0.711 and -6 to -7.5). Similarly, the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios (18.26-19.02, 15.634-15.68, and 38.25-38.82, respectively) are systematically higher in the finest detritus fraction relative to corresponding coarser fractions and bulk samples. The 87Sr/86Sr and εNd values of the finest fraction correspond with those of atmospheric dust originating from the Sahara Desert, while those of the coarse fractions are similar to loess deposits exposed in the Sinai and Negev Deserts. Pronounced excursions in the Sr-Nd-Pb isotope ratios toward more Sahara-like values coincide with the Heinrich (H) stadials 6, 5 and 1, reflecting significant increases in Saharan dust fluxes during regionally arid intervals, reflected by sharp lake level drops. Moreover, during H6 the dust came from different Saharan sources than during H1 and H5. While the relatively wet glacial climate in the Levant suppressed the transport of dust to the lake watershed, short-term hyper-arid spells during H-stadial intervals were accompanied by enhanced supply of fine Sahara dust to this region.

  20. Pressure suppression device

    International Nuclear Information System (INIS)

    Mizumachi, Wataru; Fukuda, Akira; Kitaguchi, Hidemi; Shimizu, Toshiaki.

    1976-01-01

    Object: To relieve and absorb impact wave vibrations caused by steam and non-condensed gases releasing into the pressure suppression chamber at the time of an accident. Structure: The reactor container is filled with inert gases. A safety valve attached main steam pipe is provided to permit the excessive steam to escape, the valve being communicated with the pressure suppression chamber through an exhaust pipe. In the pressure suppression chamber, a doughnut-like cylindrical outer wall is filled at its bottom with pool water to condense the high temperature vapor released through the exhaust pipe. A head portion of a vent tube which leads the exhaust pipe is positioned at the top, and a down comer and an exhaust vent tube are locked by means of steady rests. At the bottom is mounted a pressure adsorber device which adsorbs a pressure from the pool water. (Kamimura, M.)

  1. Coupling Mars' Dust and Water Cycles: Effects on Dust Lifting Vigor, Spatial Extent and Seasonality

    Science.gov (United States)

    Kahre, M. A.; Hollingsworth, J. L.; Haberle, R. M.; Montmessin, F.

    2012-01-01

    The dust cycle is an important component of Mars' current climate system. Airborne dust affects the radiative balance of the atmosphere, thus greatly influencing the thermal and dynamical state of the atmosphere. Dust raising events on Mars occur at spatial scales ranging from meters to planet-wide. Although the occurrence and season of large regional and global dust storms are highly variable from one year to the next, there are many features of the dust cycle that occur year after year. Generally, a low-level dust haze is maintained during northern spring and summer, while elevated levels of atmospheric dust occur during northern autumn and winter. During years without global-scale dust storms, two peaks in total dust loading were observed by MGS/TES: one peak occurred before northern winter solstice at Ls 200-240, and one peak occurred after northern winter solstice at L(sub s) 305-340. These maxima in dust loading are thought to be associated with transient eddy activity in the northern hemisphere, which has been observed to maximize pre- and post-solstice. Interactive dust cycle studies with Mars General Circulation Models (MGCMs) have included the lifting, transport, and sedimentation of radiatively active dust. Although the predicted global dust loadings from these simulations capture some aspects of the observed dust cycle, there are marked differences between the simulated and observed dust cycles. Most notably, the maximum dust loading is robustly predicted by models to occur near northern winter solstice and is due to dust lifting associated with down slope flows on the flanks of the Hellas basin. Thus far, models have had difficulty simulating the observed pre- and post- solstice peaks in dust loading. Interactive dust cycle studies typically have not included the formation of water ice clouds or their radiative effects. Water ice clouds can influence the dust cycle by scavenging dust from atmosphere and by interacting with solar and infrared radiation

  2. Thyroxin hormone suppression treatment

    International Nuclear Information System (INIS)

    Samuel, A.M.

    1999-01-01

    One of the important modalities of treatment of thyroid cancer (TC) after surgery is the administration of thyroxin as an adjuvant treatment. The analysis supports the theory that thyroid suppression plays an important role in patient management. 300 μg of thyroxin, as this is an adequate dose for suppression is given. Ideally the dose should be tailored by testing s-TSH levels. However, since a large number of the patients come from out station cities and villages this is impractical. We therefore depend on clinical criteria of hyperthyroid symptoms and adjust the dose. Very few patients need such adjustment

  3. House Dust Mite Respiratory Allergy

    DEFF Research Database (Denmark)

    Calderón, Moisés A; Kleine-Tebbe, Jörg; Linneberg, Allan

    2015-01-01

    Although house dust mite (HDM) allergy is a major cause of respiratory allergic disease, specific diagnosis and effective treatment both present unresolved challenges. Guidelines for the treatment of allergic rhinitis and asthma are well supported in the literature, but specific evidence on the e......Although house dust mite (HDM) allergy is a major cause of respiratory allergic disease, specific diagnosis and effective treatment both present unresolved challenges. Guidelines for the treatment of allergic rhinitis and asthma are well supported in the literature, but specific evidence...... not extend beyond the end of treatment. Finally, allergen immunotherapy has a poor but improving evidence base (notably on sublingual tablets) and its benefits last after treatment ends. This review identifies needs for deeper physician knowledge on the extent and impact of HDM allergy in respiratory disease...... and therapy of HDM respiratory allergy in practice....

  4. Collisionless damping of nonlinear dust ion acoustic wave due to dust charge fluctuation

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Chaudhuri, Tushar K.; Sarkar, Susmita; Khan, Manoranjan; Gupta, M.R.

    2002-01-01

    A dissipation mechanism for the damping of the nonlinear dust ion acoustic wave in a collisionless dusty plasma consisting of nonthermal electrons, ions, and variable charge dust grains has been investigated. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust ion acoustic wave propagation to be described by the damped Korteweg-de Vries equation. Due to the presence of nonthermal electrons, the dust ion acoustic wave admits both positive and negative potential and it suffers less damping than the dust acoustic wave, which admits only negative potential

  5. Respiratory effects of borax dust.

    Science.gov (United States)

    Garabrant, D H; Bernstein, L; Peters, J M; Smith, T J; Wright, W E

    1985-12-01

    The relation of respiratory symptoms, pulmonary function, and abnormalities of chest radiographs to estimated exposures of borax dust has been investigated in a cross sectional study of 629 actively employed borax workers. Ninety three per cent of the eligible workers participated in the study and exposures ranged from 1.1 mg/m3 to 14.6 mg/m3. Symptoms of acute respiratory irritation such as dryness of the mouth, nose, or throat, dry cough, nose bleeds, sore throat, productive cough, shortness of breath, and chest tightness were related to exposures of 4.0 mg/m3 or more, and were infrequent at exposures of 1.1 mg/m3. Symptoms of persistent respiratory irritation meeting the definition of chronic simple bronchitis were related to exposure among non-smokers. Decrements in the FEV1 as a percentage of predicted were seen among smokers who had heavy cumulative borax exposures (greater than or equal to 80 mg/m3 years) but were not seen among less exposed smokers or among non-smokers. Radiographic abnormalities were uncommon and were not related to dust exposure. Borax dust appears to act as a simple respiratory irritant and perhaps causes small changes in the FEV1 among smokers who are heavily exposed.

  6. Dust-Tolerant Intelligent Electrical Connection System

    Science.gov (United States)

    Lewis, Mark; Dokos, Adam; Perotti, Jose; Calle, Carlos; Mueller, Robert; Bastin, Gary; Carlson, Jeffrey; Townsend, Ivan, III; Immer, Chirstopher; Medelius, Pedro

    2012-01-01

    Faults in wiring systems are a serious concern for the aerospace and aeronautic (commercial, military, and civilian) industries. Circuit failures and vehicle accidents have occurred and have been attributed to faulty wiring created by open and/or short circuits. Often, such circuit failures occur due to vibration during vehicle launch or operation. Therefore, developing non-intrusive fault-tolerant techniques is necessary to detect circuit faults and automatically route signals through alternate recovery paths while the vehicle or lunar surface systems equipment is in operation. Electrical connector concepts combining dust mitigation strategies and cable diagnostic technologies have significant application for lunar and Martian surface systems, as well as for dusty terrestrial applications. The dust-tolerant intelligent electrical connection system has several novel concepts and unique features. It combines intelligent cable diagnostics (health monitoring) and automatic circuit routing capabilities into a dust-tolerant electrical umbilical. It retrofits a clamshell protective dust cover to an existing connector for reduced gravity operation, and features a universal connector housing with three styles of dust protection: inverted cap, rotating cap, and clamshell. It uses a self-healing membrane as a dust barrier for electrical connectors where required, while also combining lotus leaf technology for applications where a dust-resistant coating providing low surface tension is needed to mitigate Van der Waals forces, thereby disallowing dust particle adhesion to connector surfaces. It also permits using a ruggedized iris mechanism with an embedded electrodynamic dust shield as a dust barrier for electrical connectors where required.

  7. Ocular toxicity of authentic lunar dust.

    Science.gov (United States)

    Meyers, Valerie E; Garcìa, Hector D; Monds, Kathryn; Cooper, Bonnie L; James, John T

    2012-07-20

    Dust exposure is a well-known occupational hazard for terrestrial workers and astronauts alike and will continue to be a concern as humankind pursues exploration and habitation of objects beyond Earth. Humankind's limited exploration experience with the Apollo Program indicates that exposure to dust will be unavoidable. Therefore, NASA must assess potential toxicity and recommend appropriate mitigation measures to ensure that explorers are adequately protected. Visual acuity is critical during exploration activities and operations aboard spacecraft. Therefore, the present research was performed to ascertain the ocular toxicity of authentic lunar dust. Small (mean particle diameter = 2.9 ± 1.0 μm), reactive lunar dust particles were produced by grinding bulk dust under ultrapure nitrogen conditions. Chemical reactivity and cytotoxicity testing were performed using the commercially available EpiOcularTM assay. Subsequent in vivo Draize testing utilized a larger size fraction of unground lunar dust that is more relevant to ocular exposures (particles lunar dust was minimally irritating. Minor irritation of the upper eyelids was noted at the 1-hour observation point, but these effects resolved within 24 hours. In addition, no corneal scratching was observed using fluorescein stain. Low-titanium mare lunar dust is minimally irritating to the eyes and is considered a nuisance dust for ocular exposure. No special precautions are recommended to protect against ocular exposures, but fully shielded goggles may be used if dust becomes a nuisance.

  8. Pressure suppressing device

    International Nuclear Information System (INIS)

    Naito, Makoto.

    1980-01-01

    Purpose: To prevent the pressure in the reactor container from excessively increasing even when vapor leaks from the dry well to a space of the suppression chamber, without passing though the suppression pool at the time of loss of coolant accident. Constitution: When vapor of a high temperature and a high pressure at the time of loss of coolant accident flows from the dry well to the suppression chamber without passing through suppression pool water, vapor dose not condense with pool water, and therefore the pressure within the chamber abnormally increases. For this reason, this abnormal pressure is detected by a pressure detector thereby to start the operations of a blower and a pump. By starting the blower, the pressure in the dry well becomes lower than the pressure in the chamber, and vapor entirely passes through the pool water and entirely condenses with the pool water. By starting the pump, the pool water is sprayed over the space of the chamber, and vapor in the space is condensed. (Yoshino, Y.)

  9. Dust characterisation for hot gas filters

    Energy Technology Data Exchange (ETDEWEB)

    Dockter, B.; Erickson, T.; Henderson, A.; Hurley, J.; Kuehnel, V.; Katrinak, K.; Nowok, J.; O`Keefe, C.; O`Leary, E.; Swanson, M.; Watne, T. [University of North Dakota, Grand Forks, ND (United States). Energy and Environmental Research Center (UNDEERC)

    1998-03-01

    Hot gas filtration to remove particulates from the gas flow upstream of the gas turbine is critical to the development of many of the advanced coal-fired power generation technologies such as the Air Blown Gasification Cycle (ABGC), a hybrid gasification combined cycle being developed in the UK. Ceramic candle filters are considered the most promising technology for this purpose. Problems of mechanical failure and of `difficult-to-clean` dusts causing high pressure losses across the filter elements need to be solved. The project investigated the behaviour of high-temperature filter dusts, and the factors determining the ease with which they can be removed from filters. The high-temperature behaviour of dusts from both combustion and gasification systems was investigated. Dust samples were obtained from full-scale demonstration and pilot-scale plant operating around the world. Dust samples were also produced from a variety of coals, and under several different operating conditions, on UNDEERC`s pilot-scale reactor. Key factors affecting dust behaviour were examined, including: the rates of tensile strength developing in dust cakes; the thermochemical equilibria pertaining under filtration conditions; dust adhesivity on representative filter materials; and the build-up and cleaning behaviour of dusts on representative filter candles. The results obtained confirmed the importance of dust temperature, dust cake porosity, cake liquid content, and particle size distribution in determining the strength of a dust cake. An algorithm was developed to indicate the likely sticking propensity of dusts as a function of coal and sorbent composition and combustion conditions. This algorithm was incorporated into a computer package which can be used to judge the degree of difficulty in filter cleaning that can be expected to arise in a real plant based on operating parameters and coal analyzes. 6 figs.

  10. House dust in seven Danish offices

    Science.gov (United States)

    Mølhave, L.; Schneider, T.; Kjærgaard, S. K.; Larsen, L.; Norn, S.; Jørgensen, O.

    Floor dust from Danish offices was collected and analyzed. The dust was to be used in an exposure experiment. The dust was analyzed to show the composition of the dust which can be a source of airborne dust indoors. About 11 kg of dust from vacuum cleaner bags from seven Danish office buildings with about 1047 occupants (12 751 m 2) was processed according to a standardized procedure yielding 5.5 kg of processed bulk dust. The bulk dust contained 130.000-160.000 CFU g -1 microorganisms and 71.000-90.000 CFU g -1 microfungi. The content of culturable microfungi was 65-123 CFU 30 g -1 dust. The content of endotoxins ranged from 5.06-7.24 EU g -1 (1.45 ng g -1 to 1.01 ng g -1). Allergens (ng g -1) were from 147-159 (Mite), 395-746 (dog) and 103-330 (cat). The macro molecular organic compounds (the MOD-content) varied from 7.8-9.8 mg g -1. The threshold of release of histamine from basophil leukocytes provoked by the bulk dust was between 0.3 and 1.0 mg ml -1. The water content was 2% (WGT) and the organic fraction 33%. 6.5-5.9% (dry) was water soluble. The fiber content was less than 0.2-1.5% (WGT) and the desorbable VOCs was 176-319 μg g -1. Most of the VOC were aldehydes. However, softeners for plastic (DBP and DEHP) were present. The chemical composition includes human and animal skin fragments, paper fibers, glass wool, wood and textilefibers and inorganic and metal particles. The sizes ranged from 0.001-1 mm and the average specific density was 1.0 g m -3. The bulk dust was resuspended and injected into an exposure chamber. The airborne dust was sampled and analyzed to illustrate the exposures that can result from sedimented dirt and dust. The airborne dust resulting from the bulk dust reached concentrations ranging from 0.26-0.75 mg m -3 in average contained 300-170 CFU m -3. The organic fraction was from 55-70% and the water content about 2.5% (WGT). The content of the dust was compared to the similar results reported in the literature and its toxic potency is

  11. Characterization of high concentration dust generator

    International Nuclear Information System (INIS)

    Shimura, Toichiro; Yokochi, Akira

    1999-01-01

    This paper describes the development of fluidized bed type high concentration dust generator that keeps for long period dust concentration range of about 10 mg/m 3 for the study of working place monitoring system and evaluation of respirator. The generator is keeping constant powder in fluidized bed for keeping the dust concentration. It is necessary to keep constant feeding rate of powder in order to keep the quantity of dust in the fluidized bed. Our generator enables to obtain constant feeding rate by a screw feeder and by using mixed powder with fluidising particles (glass beads) before feeding. The generator produces high concentration dust of 11.3 mg/m 3 ± 1.0 mg/m 3 for about 5 hours and keeps the dust size 4.2-4.6 μm in mass median aerodynamic diameter with reasonable reproducibility. (author)

  12. Molecules and dust in Cassiopeia A

    DEFF Research Database (Denmark)

    Biscaro, Chiara; Cherchneff, Isabelle

    2016-01-01

    We study the dust evolution in the supernova remnant Cassiopeia A. We follow the processing of dust grains that formed in the Type II-b supernova ejecta by modelling the sputtering of grains. The dust is located in dense ejecta clumps that are crossed by the reverse shock. We also investigate......-rich clumps that correspond to the outermost carbon-rich ejecta zone. We consider the various dust components that form in the supernova, several reverse shock velocities and inter-clump gas temperatures, and derive grain-size distributions and masses for the dust as a function of time. Both non...... and size, and the shock velocity in the clump. A Type II-b SN forms small grains that are sputtered within the clumps and in the inter-clump medium. For Cas A, silicate grains do not survive thermal sputtering in the inter-clump medium, while alumina, silicon carbide, and carbon dust may survive...

  13. Active Dust Experiment in the Mesosphere

    International Nuclear Information System (INIS)

    Norberg, Carol; Pellinen-Wannberg, Asta

    2008-01-01

    The mesosphere stretches from an altitude of about 50 to 90 km above the Earth's surface. Meteors entering the Earth's atmosphere are believed to ablate and hence give rise to a thin layer of dust particles in the upper part of the Earth's mesosphere. It seems that the dust is most dense in a layer that lies between 80 and 90 km. The dust particles are thought to have sizes of a few to tens of nanometers. Efforts have been made to measure these particles using rockets and radar techniques with limited success. We propose to release dust into the mesosphere over northern Sweden at a height of about 90 km and observe the released dust using the EISCAT radar system. The dust will be launched from the Swedish Space Corporation Esrange Space Centre on a single-stage Improved-Orion rocket that will be launched so that its flight path will be in the radar field of view.

  14. Dust observations by PFS on Mars Express

    Science.gov (United States)

    Zasova, L. V.; Formisano, V.; Moroz, V. I.; Grassi, D.; Ignatiev, N. I.; Blecka, M. I.; Maturilli, A.; Palomba, E.; Piccioni, G.; Pfs Team

    Dust is always present in the Martian atmosphere with opacity, which changes from values below 0.1 (at 9 μ m) up to several units during the dust storms. From the thermal IR (LW channel of PFS) the dust opacity is retrieved in a self consistent way together with the temperature profile from the same spectrum A preliminary investigation along the orbit, which comes through Hellas, shows that the value of dust opacity anticorrelates with surface altitude. From -70 to +25 of latitude the vertical dust distribution follows the exponential low with the scale of 12 km, which corresponds to the gaseous scale height near noon and indicates for well mixed condition. The dust opacity, corresponding to the zero surface altitude, is found of 0.25+-0.05. More detailed investigations of all available data will be presented, including analysis of both short- and long- wavelength spectra of PFS.

  15. Formation and dissociation of dust molecules in dusty plasma

    International Nuclear Information System (INIS)

    Yan Jia; Feng Fan; Liu Fucheng; Dong Lifang; He Yafeng

    2016-01-01

    Dust molecules are observed in a dusty plasma experiment. By using measurements with high spatial resolution, the formation and dissociation of the dust molecules are studied. The ion cloud in the wake of an upper dust grain attracts the lower dust grain nearby. When the interparticle distance between the upper dust grain and the lower one is less than a critical value, the two dust grains would form a dust molecule. The upper dust grain always leads the lower one as they travel. When the interparticle distance between them is larger than the critical value, the dust molecule would dissociate. (paper)

  16. Trace metals in urban road dust

    International Nuclear Information System (INIS)

    Randazzo, Loredana Antonella; Dongarra, Gaetano; Manno, Emanuela; Varrica, Daniela

    2006-01-01

    Heavy metals associated with urban road dust is a matter for concern as they may have serious effects on biological systems. The bioavailability and potential toxicity of metals bound to urban dust is related to the specific chemical form of the element. In the present article are reported the determinations and chemical speciation of As, Ba, Cr, Cu, Mo, Ni, Pb and Zn in six samples of road dust collected within the urban centre and the outskirts of Palermo [it

  17. Cylindrical dust acoustic waves with transverse perturbation

    International Nuclear Information System (INIS)

    Xue Jukui

    2003-01-01

    The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation

  18. The control and prevention of dust explosions

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    Papers presented discussed: explosion characteristics and hybrid mixtures explosion characteristics and influencing factors, propagation of dust explosions in ducts, prevention of dust explosions, desensitization, explosion-proof type of construction, explosion pressure relief, optical flame barriers, slide-valves for explosion protection, Ventex explosion barrier valves, grinding and mixing plants, spray driers, dust explosions in silos, and explosion-proof bucket elevators. One paper has been abstracted separately.

  19. Dust control at Yucca Mountain project

    International Nuclear Information System (INIS)

    Kissell, F.; Jurani, R.; Dresel, R.; Reaux, C.

    1999-01-01

    This report describes actions taken to control silica dust at the Yucca Mountain Exploratory Studies Facility, a tunnel located in Southern Nevada that is part of a scientific program to determine site suitability for a potential nuclear waste repository. The rock is a volcanic tuff containing significant percentages of both quartz and cristobalite. Water use for dust control was limited because of scientific test requirements, and this limitation made dust control a difficult task. Results are reported for two drifts, called the Main Loop Drift and the Cross Drift. In the Main Loop Drift, dust surveys and tracer gas tests indicated that air leakage from the TBM head, the primary ventilation duct, and movement of the conveyor belt were all significant sources of dust. Conventional dust control approaches yielded no significant reductions in dust levels. A novel alternative was to install an air cleaning station on a rear deck of the TBM trailing gear. It filtered dust from the contaminated intake air and discharged clean air towards the front of the TBM. The practical effect was to produce dust levels below the exposure limit for all TBM locations except close to the head. In the Cross Drift, better ventilation and an extra set of dust seals on the TBM served to cut down the leakage of dust from the TBM cutter head. However, the conveyor belt was much dustier than the belt in the main loop drift. The problem originated with dirt on the bottom of the belt return side and much spillage from the belt top side. Achieving lower dust levels in hard rock tunneling operations will require new approaches as well as a more meticulous application of existing technology. Planning for dust control will require specific means to deal with dust that leaks from the TBM head, dust that originates with leaky ventilation systems, and dust that comes from conveyor belts. Also, the application of water could be more efficient if automatic controls were used to adjust the water flow

  20. Beryllium dust generation resulting from plasma bombardment

    International Nuclear Information System (INIS)

    Doerner, R.; Mays, C.

    1997-01-01

    The beryllium dust resulting from erosion of beryllium samples subjected to plasma bombardment has been measured in PISCES-B. Loose surface dust was found to be uniformly distributed throughout the device and accounts for 3% of the eroded material. A size distribution measurement of the loose surface dust shows an increasing number of particles with decreasing diameter. Beryllium coatings on surfaces with a line of sight view of the target interaction region account for an additional 33% of the eroded beryllium material. Flaking of these surface layers is observed and is thought to play a significant role in dust generation inside the vacuum vessel. (orig.)

  1. Control of dust production in ITER

    International Nuclear Information System (INIS)

    Rodriguez-Rodrigo, L.; Ciattaglia, S.; Elbez-Uzan, J.

    2006-01-01

    In the last years dust has been observed in a number of fusion devices and is being studied more in detail for understanding in particular the physical phenomena related to its formation, its composition, physical and chemical characteristics, and the amount of produced dust. The extrapolation of dust formation to ITER predicts (with large error bars), a large mass of dust production with a scattered size distribution. To evaluate the impact of dust on safety, assumptions have also been made on radionuclide inventory, and mobility in off-normal events, as well as any postulated contributions the dust may make to effluents or accidental releases. Solid activation products in structures are generally not readily mobilisable in incidental and accidental situations, so that activated dust, tritium and activated corrosions products are the important in-vessel source terms in postulated scenarios that assume a mobilisation and release of some fraction of this inventory. Such a release would require the simultaneous leak or bypass of several robust confinement barriers. Further concerns for dust may be the potential for chemical reactions between dust and coolant in the event of an in-vessel leak, and the theoretical possibility of a dust explosion, either of which could in principle cause a pressure rise that challenges one or more of the confinement barriers. Although these hazards can - and will - be controlled by other measures in the ITER design, application of the principle of Defence in Depth dictates that the dust inventory should also be minimised and controlled to prevent the potential hazard. A well-coordinated R-and-D programme is required to support this dust production control. This document provides from the safety point of view, an overview of existing data given in '' Dossier d'Options de Surete '', the first safety report presented in 2001 to the French Safety Authorities, and ITER documents; it also gathers information on status of studies on activated

  2. J/Ψ suppression

    International Nuclear Information System (INIS)

    Giubellino, P.; Abreu, M.C.; Alessandro, B.; Alexa, C.; Arnaldi, R.; Astruc, J.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Bellaiche, F.; Beole, S.; Boldea, V.; Bordalo, P.; Bussiere, A.; Capony, V.; Casagrande, L.; Castor, J.; Chambon, T.; Chaurand, B.; Chevrot, I.; Cheynis, B.; Chiavassa, E.; Cicalo, C.; Comets, M.P.; Constantinescu, S.; Cruz, J.; De Falco, A.; De Marco, N.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Espagnon, B.; Fargeix, J.; Filippov, S.N.; Fleuret, F.; Force, P.; Gallio, M.; Gavrilov, Y.K.; Gerschel, C.; Giubellino, P.; Golubeva, M.B.; Gonin, M.; Grigorian, A.A.; Grossiord, J.Y.; Guber, F.F.; Guichard, A.; Gulkaninan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T.L.; Kluberg, L.; Kurepin, A.B.; Le Bornec, Y.; Lourenco, C.; Mac Cormick, M.; Macciotta, P.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Mehrabyan, S.; Mourgues, S.; Musso, A.; Ohlsson-Malek, F.; Petiau, P.; Piccotti, A.; Pizzi, J.R.; Prado da Silva, W.L.; Puddu, G.; Quintans, C.; Racca, C.; Ramello, L.; Ramos, S.; Rato-Mendes, P.; Riccati, L.; Romana, A.; Sartori, S.; Saturnini, P.; Scomparin, E.; Serci, S.; Shahoyan, R.; Silva, S.; Soave, C.; Sonderegger, P.; Tarrago, X.; Temnikov, P.; Topilskaya, N.S.; Usai, G.; Vale, C.; Vercellin, E.; Willis, N.

    1999-01-01

    The cross section for J/Ψ production in Pb-Pb interactions at 158 GeV per nucleon is measured at the CERN SPS by the NA50 experiment. The final results from the 1995 run are presented here together with preliminary ones from the high-statistics 1996 run. An anomalous J/Ψ suppression is observed in Pb-Pb collisions as compared to extrapolations of the previous results obtained by the NA38 experiment with proton and lighter ion beams. The results of the two runs are in good agreement. The results from the 1996 run allow the study of the onset of the anomalous suppression within the same set of data, showing evidence of a sharp change of behaviour around a value of neutral transverse energy, as measured by our electromagnetic calorimeter, of about 50 GeV

  3. Integrative Analysis of Desert Dust Size and Abundance Suggests Less Dust Climate Cooling

    Science.gov (United States)

    Kok, Jasper F.; Ridley, David A.; Zhou, Qing; Miller, Ron L.; Zhao, Chun; Heald, Colette L.; Ward, Daniel S.; Albani, Samuel; Haustein, Karsten

    2017-01-01

    Desert dust aerosols affect Earths global energy balance through interactions with radiation, clouds, and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, and the climate impact of possible future alterations in dust loading is similarly disputed. Here we use an integrative analysis of dust aerosol sizes and abundance to constrain the climatic impact of dust through direct interactions with radiation. Using a combination of observational, experimental, and model data, we find that atmospheric dust is substantially coarser than represented in current climate models. Since coarse dust warms global climate, the dust direct radiative effect (DRE) is likely less cooling than the 0.4 W m superscript 2 estimated by models in a current ensemble. We constrain the dust DRE to -0.20 (-0.48 to +0.20) W m superscript 2, which suggests that the dust DRE produces only about half the cooling that current models estimate, and raises the possibility that dust DRE is actually net warming the planet.

  4. Carbohydrate and protein contents of grain dusts in relation to dust morphology.

    Science.gov (United States)

    Dashek, W V; Olenchock, S A; Mayfield, J E; Wirtz, G H; Wolz, D E; Young, C A

    1986-01-01

    Grain dusts contain a variety of materials which are potentially hazardous to the health of workers in the grain industry. Because the characterization of grain dusts is incomplete, we are defining the botanical, chemical, and microbial contents of several grain dusts collected from grain elevators in the Duluth-Superior regions of the U.S. Here, we report certain of the carbohydrate and protein contents of dusts in relation to dust morphology. Examination of the gross morphologies of the dusts revealed that, except for corn, each dust contained either husk or pericarp (seed coat in the case of flax) fragments in addition to respirable particles. When viewed with the light microscope, the fragments appeared as elongated, pointed structures. The possibility that certain of the fragments within corn, settled, and spring wheat were derived from cell walls was suggested by the detection of pentoses following colorimetric assay of neutralized 2 N trifluoroacetic acid hydrolyzates of these dusts. The presence of pentoses together with the occurrence of proteins within water washings of grain dusts suggests that glycoproteins may be present within the dusts. With scanning electron microscopy, each dust was found to consist of a distinct assortment of particles in addition to respirable particles. Small husk fragments and "trichome-like" objects were common to all but corn dust. Images FIGURE 4. FIGURE 5. PMID:3709476

  5. The Electric Environment of Martian Dust Devils

    Science.gov (United States)

    Barth, E. L.; Farrell, W. M.; Rafkin, S. C.

    2017-12-01

    While Martian dust devils have been monitored through decades of observations, we have yet to study their possible electrical effects from in situ instrumentation. However, evidence for the existence of active electrodynamic processes on Mars is provided by laboratory studies of analog material and field campaigns of dust devils on Earth. We have enabled our Mars regional scale atmospheric model (MRAMS) to estimate an upper limit on electric fields generated through dust devil circulations by including charged particles as defined from the Macroscopic Triboelectric Simulation (MTS) code. MRAMS is used to investigate the complex physics of regional, mesoscale, and microscale atmospheric phenomena on Mars; it is a 3-D, nonhydrostatic model, which permits the simulation of atmospheric flows with large vertical accelerations, such as dust devils. MTS is a 3-D particle code which quantifies charging associated with swirling, mixing dust grains; grains of pre-defined sizes and compositions are placed in a simulation box and allowed to move under the influence of winds and gravity. Our MRAMS grid cell size makes our results most applicable to dust devils of a few hundred meters in diameter. We have run a number of simulations to understand the sensitivity of the electric field strength to the particle size and abundance and the amount of charge on each dust grain. We find that Efields can indeed develop in Martian dust convective features via dust grain filtration effects. The overall value of these E-fields is strongly dependent upon dust grain size, dust load, and lifting efficiency, and field strengths can range from 100s of mV/m to 10s of kV/m.

  6. Dust emission at Franklin Lake Playa, Mojave Desert (USA): Response to meteorological and hydrologic changes 2005-2008

    Science.gov (United States)

    Reynolds, Richard L.; Bogle, Rian; Vogel, John; Goldstein, Harland L.; Yount, James

    2009-01-01

    Playa type, size, and setting; playa hydrology; and surface-sediment characteristics are important controls on the type and amount of atmospheric dust emitted from playas. Soft, evaporite-rich sediment develops on the surfaces of some Mojave Desert (USA) playas (wet playas), where the water table is shallow (monitored between March 2005 and April 2008. The dust record, based on day-time remote digital camera images captured during high wind, and compared with a nearby precipitation record, shows that aridity suppresses dust emission. High frequency of dust generation appears to be associated with relatively wet periods, identified as either heavy precipitation events or sustained regional precipitation over a few months. Several factors may act separately or in combination to account for this relation. Dust emission may respond rapidly to heavy precipitation when the dissolution of hard, wind-resistant evaporite mineral crusts is followed by the development of soft surfaces with thin, newly formed crusts that are vulnerable to wind erosion and (or) the production of loose aggregates of evaporite minerals that are quickly removed by even moderate winds. Dust loading may also increase when relatively high regional precipitation leads to decreasing depth to the water table, thereby increasing rates of vapor discharge, development of evaporite minerals, and temporary softening of playa surfaces. The seasonality of wind strength was not a major factor in dust-storm frequency at the playa. The lack of major dust emissions related to flood-derived sediment at Franklin Lake playa contrasts with some dry-lake systems elsewhere that may produce large amounts of dust from flood sediments. Flood sediments do not commonly accumulate on the surface of Franklin Lake playa because through-going drainage prevents frequent inundation and deposition of widespread flood sediment.

  7. Migration, Masculinity and the Fugitive State of Mind in the Irish Emigrant Footballer Autobiography: the Case of Paul McGrath

    Directory of Open Access Journals (Sweden)

    Marcus Free

    2010-03-01

    Full Text Available The ‘confessional’ autobiography has become a popular variant of professional football autobiography in Britain. Co-written ‘autobiographies’ by prominent former emigrant Irish or Irish descended international footballers have featured prominently in this sub-genre.  Their ‘confessions’ of alcoholism, gambling, infidelity, irresponsibility towards partners or dependents, or underlying ontological insecurity might be seen as an insightful engagement with their lives as male footballers in Britain.  However, focusing on two autobiographies of Paul McGrath, and reading these ‘troubled’ accounts using psychoanalytic perspectives on sport, migration and masculinity, it is argued that they are contradictory texts which embody a peculiar variation on the emigrant “fugitive state of mind” (Davar, 1996, both approximating and deferring mature, reflexive engagement with the social and cultural construction of identity, allowing them to occupy a liminal but discontent imaginary space in which adolescent masculinity can be indefinitely extended.   The homosocial world of men’s professional football is a key factor in this.

  8. Fugitive methane leak detection using mid-infrared hollow-core photonic crystal fiber containing ultrafast laser drilled side-holes

    Science.gov (United States)

    Karp, Jason; Challener, William; Kasten, Matthias; Choudhury, Niloy; Palit, Sabarni; Pickrell, Gary; Homa, Daniel; Floyd, Adam; Cheng, Yujie; Yu, Fei; Knight, Jonathan

    2016-05-01

    The increase in domestic natural gas production has brought attention to the environmental impacts of persistent gas leakages. The desire to identify fugitive gas emission, specifically for methane, presents new sensing challenges within the production and distribution supply chain. A spectroscopic gas sensing solution would ideally combine a long optical path length for high sensitivity and distributed detection over large areas. Specialty micro-structured fiber with a hollow core can exhibit a relatively low attenuation at mid-infrared wavelengths where methane has strong absorption lines. Methane diffusion into the hollow core is enabled by machining side-holes along the fiber length through ultrafast laser drilling methods. The complete system provides hundreds of meters of optical path for routing along well pads and pipelines while being interrogated by a single laser and detector. This work will present transmission and methane detection capabilities of mid-infrared photonic crystal fibers. Side-hole drilling techniques for methane diffusion will be highlighted as a means to convert hollow-core fibers into applicable gas sensors.

  9. The dust acoustic wave in a bounded dusty plasma with strong electrostatic interactions between dust grains

    International Nuclear Information System (INIS)

    Shukla, Nitin; Shukla, P.K.

    2011-01-01

    The dispersion relation for the dust acoustic wave (DAW) in an unmagnetized dusty plasma cylindrical waveguide is derived, accounting for strong electrostatic interactions between charged dust grains. It is found that the boundary effect limits the radial extent of the DAW. The present result should be helpful for understanding the frequency spectrum of the DAW in a dusty plasma waveguide with strongly coupled charged dust grains. - Highlights: → We study the dust acoustic wave (DAW) in a bounded plasma. → We account for interactions between dust grains. → The boundary effect limits the radial extent of the DAW.

  10. Radioactive dust in the air

    Energy Technology Data Exchange (ETDEWEB)

    Yano, N

    1956-01-01

    An electric precipitator is used to collect dust in the air because its collection efficiency for radioactive substances is up to 10 times that of the impactor of filter-paper types. About 10 cu m of air is filtered during 5 hours, and the trapped dust is measured more than 24 hours after collection to avoid the influence of naturally active substances. The average radioactivity of the air is approximately 10/sup -16/ c/cc. During the period of observation 4 peaks occurred. The dates and maximum levels of artificial activity, respectively, are November 4 to 10, 1954, 1.2 x 10/sup -7/ uc/l; April 11 to 13, 1955, 4.3 x 10/sup -8/ uc/l; November 25 to 28, 1955, maximum unknown; and March 22 to 25, 1956, 1.- x 10/sup -7/ uc/l. The presumed dates and places of detonation corresponding to the peaks are October 31, 1954 northwest of Japan; March 29, 1955, Nevada, US; November 22, 1955, near L. Baikal, USSR; and March 13 to 15, 1956 unknown.

  11. Comet Dust After Deep Impact

    Science.gov (United States)

    Wooden, Diane H.; Harker, David E.; Woodward, Charles E.

    2006-01-01

    When the Deep Impact Mission hit Jupiter Family comet 9P/Tempel 1, an ejecta crater was formed and an pocket of volatile gases and ices from 10-30 m below the surface was exposed (A Hearn et aI. 2005). This resulted in a gas geyser that persisted for a few hours (Sugita et al, 2005). The gas geyser pushed dust grains into the coma (Sugita et a1. 2005), as well as ice grains (Schulz et al. 2006). The smaller of the dust grains were submicron in radii (0-25.3 micron), and were primarily composed of highly refractory minerals including amorphous (non-graphitic) carbon, and silicate minerals including amorphous (disordered) olivine (Fe,Mg)2SiO4 and pyroxene (Fe,Mg)SiO3 and crystalline Mg-rich olivine. The smaller grains moved faster, as expected from the size-dependent velocity law produced by gas-drag on grains. The mineralogy evolved with time: progressively larger grains persisted in the near nuclear region, having been imparted with slower velocities, and the mineralogies of these larger grains appeared simpler and without crystals. The smaller 0.2-0.3 micron grains reached the coma in about 1.5 hours (1 arc sec = 740 km), were more diverse in mineralogy than the larger grains and contained crystals, and appeared to travel through the coma together. No smaller grains appeared at larger coma distances later (with slower velocities), implying that if grain fragmentation occurred, it happened within the gas acceleration zone. These results of the high spatial resolution spectroscopy (GEMINI+Michelle: Harker et 4. 2005, 2006; Subaru+COMICS: Sugita et al. 2005) revealed that the grains released from the interior were different from the nominally active areas of this comet by their: (a) crystalline content, (b) smaller size, (c) more diverse mineralogy. The temporal changes in the spectra, recorded by GEMIM+Michelle every 7 minutes, indicated that the dust mineralogy is inhomogeneous and, unexpectedly, the portion of the size distribution dominated by smaller grains has

  12. The management of house dust mite allergies

    NARCIS (Netherlands)

    Bronswijk, van J.E.M.H.; Schober, G.; Kniest, F.M.

    1990-01-01

    A safe and practical home sanitation procedure for the removal of house dust mites (Dermatophagoides pteronyssinus) and their allergens is described. The severity of mite infestation was assessed with the use of the Acarex test, which measures the concentration of guanine in house dust, and all

  13. A rotating dust cloud in general relativity

    International Nuclear Information System (INIS)

    Bonnor, W.B.

    1977-01-01

    An axially symmetric, stationary exact solution of Einstein's equations for dust is studied. It is asymptotically flat, and represents a rotating dust cloud extending tenuously to infinity, containing a singularity at the centre. An explanation is given as to why there exists no corresponding solution in Newtonian theory. (author)

  14. Dust coagulation in protoplanetary disks : porosity matters

    NARCIS (Netherlands)

    Ormel, C. W.; Spaans, M.; Tielens, A. G. G. M.

    Context. Sticking of colliding dust particles through van der Waals forces is the first stage in the grain growth process in protoplanetary disks, eventually leading to the formation of comets, asteroids and planets. A key aspect of the collisional evolution is the coupling between dust and gas

  15. Correlation between Yellow Dust and Radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    AIZaabia, Mouza A [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Byoung-Jik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2015-10-15

    In East Asia, yellow dust or Asian Dust (AD) outbreaks are among the largest contributors of wind-blown dust that carry natural and anthropogenic radionuclides and subsequently alter their concentration and distribution throughout the environment. Although the Korean Peninsula has been experiencing AD events since ancient times, the research has tended to focus on the transport routes and characteristics of AD, rather than on its impact on radionuclide activity levels. This paper examines the relationship between radionuclide concentration in the air and the frequency of dusty days in South Korea during AD intrusion events. It also investigates whether increased radionuclide concentration is a function of either more mass or more dust contamination. In this study, significant linear correlations of gamma-emitting radionuclides were found with mass of dust and occurrence frequency of AD. Regardless of the source origin of the dust, {sup 137}Cs and {sup 7}Be concentration primarily depended on dust mass in the filter. Nonetheless, the correlations were greatly distorted in 2011 and in the spring season, particularly the correlations with AD days that were far below that of the correlations obtained for the whole study period. A possible explanation of these conflicting results is that a change in the dust source could appreciably alter the concentration, deposition, and distribution of airborne radionuclides.

  16. Correlation between Yellow Dust and Radioactivity

    International Nuclear Information System (INIS)

    AIZaabia, Mouza A; Kim, Byoung-Jik

    2015-01-01

    In East Asia, yellow dust or Asian Dust (AD) outbreaks are among the largest contributors of wind-blown dust that carry natural and anthropogenic radionuclides and subsequently alter their concentration and distribution throughout the environment. Although the Korean Peninsula has been experiencing AD events since ancient times, the research has tended to focus on the transport routes and characteristics of AD, rather than on its impact on radionuclide activity levels. This paper examines the relationship between radionuclide concentration in the air and the frequency of dusty days in South Korea during AD intrusion events. It also investigates whether increased radionuclide concentration is a function of either more mass or more dust contamination. In this study, significant linear correlations of gamma-emitting radionuclides were found with mass of dust and occurrence frequency of AD. Regardless of the source origin of the dust, 137 Cs and 7 Be concentration primarily depended on dust mass in the filter. Nonetheless, the correlations were greatly distorted in 2011 and in the spring season, particularly the correlations with AD days that were far below that of the correlations obtained for the whole study period. A possible explanation of these conflicting results is that a change in the dust source could appreciably alter the concentration, deposition, and distribution of airborne radionuclides

  17. Measurement of nicotine in household dust

    International Nuclear Information System (INIS)

    Kim, Sungroul; Aung, Ther; Berkeley, Emily; Diette, Gregory B.; Breysse, Patrick N.

    2008-01-01

    An analytical method of measuring nicotine in house dust was optimized and associations among three secondhand smoking exposure markers were evaluated, i.e., nicotine concentrations of both house dust and indoor air, and the self-reported number of cigarettes smoked daily in a household. We obtained seven house dust samples from self-reported nonsmoking homes and 30 samples from smoking homes along with the information on indoor air nicotine concentrations and the number of cigarettes smoked daily from an asthma cohort study conducted by the Johns Hopkins Center for Childhood Asthma in the Urban Environment. House dust nicotine was analyzed by isotope dilution gas chromatography-mass spectrometry (GC/MS). Using our optimized method, the median concentration of nicotine in the dust of self-reported nonsmoking homes was 11.7 ng/mg while that of smoking homes was 43.4 ng/mg. We found a substantially positive association (r=0.67, P<0.0001) between house dust nicotine concentrations and the numbers of cigarettes smoked daily. Optimized analytical methods showed a feasibility to detect nicotine in house dust. Our results indicated that the measurement of nicotine in house dust can be used potentially as a marker of longer term SHS exposure

  18. 30 CFR 56.9315 - Dust control.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Dust control. 56.9315 Section 56.9315 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... control. Dust shall be controlled at muck piles, material transfer points, crushers, and on haulage roads...

  19. Role of dust in H II regions

    International Nuclear Information System (INIS)

    Sarazin, C.L.

    1975-01-01

    The purpose of this dissertation is to determine quantitatively the effects of U.V. absorbing dust on H II regions, and compare these effects with observations. Many observations indicate that dust grains are present within H II regions. An analytic theory is presented which describes all three of the effects of dust in H II regions. Although this model is relatively crude, it is useful in determining the approximate size of the modifications due to dust. In order to explore this problem more carefully, detailed numerical models of H II regions with dust were constructed. The ionization and thermal structure of these model H II regions is discussed. The observational consequences of the presence of dust are explored; the optical line intensities, radio continuum and line fluxes, and infrared emission of model H II regions with dust are given. These numerical models are compared with observations of diffuse nebulae. The optical line ratios are compared to several nearby bright H II regions, and it is found that the dust models may explain several anomalies in their spectrum

  20. The Continuous Monitoring of Desert Dust using an Infrared-based Dust Detection and Retrieval Method

    Science.gov (United States)

    Duda, David P.; Minnis, Patrick; Trepte, Qing; Sun-Mack, Sunny

    2006-01-01

    Airborne dust and sand are significant aerosol sources that can impact the atmospheric and surface radiation budgets. Because airborne dust affects visibility and air quality, it is desirable to monitor the location and concentrations of this aerosol for transportation and public health. Although aerosol retrievals have been derived for many years using visible and near-infrared reflectance measurements from satellites, the detection and quantification of dust from these channels is problematic over bright surfaces, or when dust concentrations are large. In addition, aerosol retrievals from polar orbiting satellites lack the ability to monitor the progression and sources of dust storms. As a complement to current aerosol dust retrieval algorithms, multi-spectral thermal infrared (8-12 micron) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Meteosat-8 Spinning Enhanced Visible and Infrared Imager (SEVIRI) are used in the development of a prototype dust detection method and dust property retrieval that can monitor the progress of Saharan dust fields continuously, both night and day. The dust detection method is incorporated into the processing of CERES (Clouds and the Earth s Radiant Energy System) aerosol retrievals to produce dust property retrievals. Both MODIS (from Terra and Aqua) and SEVERI data are used to develop the method.

  1. Dust plume formation in the free troposphere and aerosol size distribution during the Saharan Mineral Dust Experiment in North Africa

    KAUST Repository

    Khan, Basit Ali; Stenchikov, Georgiy L.; Weinzierl, Bernadett; Kalenderski, Stoitchko; Osipov, Sergey

    2015-01-01

    , this study combines model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution

  2. Extracting lunar dust parameters from image charge signals produced by the Lunar Dust Experiment

    Science.gov (United States)

    Stanley, J.; Kempf, S.; Horanyi, M.; Szalay, J.

    2015-12-01

    The Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) is an impact ionization dust detector used to characterize the lunar dust exosphere generated by the impacts of large interplanetary particles and meteor streams (Horanyi et al., 2015). In addition to the mass and speed of these lofted particles, LDEX is sensitive to their charge. The resulting signatures of impact events therefore provide valuable information about not only the ambient plasma environment, but also the speed vectors of these dust grains. Here, impact events produced from LDEX's calibration at the Dust Accelerator Laboratory are analyzed using an image charge model derived from the electrostatic simulation program, Coulomb. We show that parameters such as dust grain speed, size, charge, and position of entry into LDEX can be recovered and applied to data collected during LADEE's seven-month mission.

  3. The pressure suppression system

    International Nuclear Information System (INIS)

    Aust, E.

    1985-01-01

    Nuclear plants with boiling water reactors have a safety containment with a pressure suppression system (PSS). Proceeding on significant self-developments, today the three PSS-lines of General Electric Co. (GE), Kraftwerk Union AG (KWU) and ASEA-ATOM are predominant, which are currently represented by the MARK III type, the KWU type 72 and the BWR 75 containment. In addition, there are special developments for the nuclear ship propulsion and for the pressurized water reactors in the Soviet Union. Key design values of the PSS allow a first valuation of its loads during a hypothetical loss-of-coolant accident. (orig.) [de

  4. Heating of Porous Icy Dust Aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Sirono, Sin-iti [Earth and Environmental Sciences, Nagoya University, Tikusa-ku, Furo-cho, Nagoya 464-8601 (Japan)

    2017-06-10

    At the beginning of planetary formation, highly porous dust aggregates are formed through coagulation of dust grains. Outside the snowline, the main component of an aggregate is H{sub 2}O ice. Because H{sub 2}O ice is formed in amorphous form, its thermal conductivity is extremely small. Therefore, the thermal conductivity of an icy dust aggregate is low. There is a possibility of heating inside an aggregate owing to the decay of radionuclides. It is shown that the temperature increases substantially inside an aggregate, leading to crystallization of amorphous ice. During the crystallization, the temperature further increases sufficiently to continue sintering. The mechanical properties of icy dust aggregates change, and the collisional evolution of dust aggregates is affected by the sintering.

  5. The relaxation of plasmas with dust particles

    International Nuclear Information System (INIS)

    Chutov, Yu.I.; Kravchenko, A.Yu.; Schram, P.P.J.M.

    1997-01-01

    Various parameters of relaxing plasmas with dust particles including the electron and ion energy distributions function are numerically simulated at various parameters of the dust particles using the PIC method and taking into account the dynamics of the dust particle charge without the assumption about the equilibrium of electrons and ions. Coulomb collisions are taken into account in the framework of the method of stochastic differential equations. The relaxation of bounded plasma clouds expanding into a vacuum as well as the relaxation of a uniform plasma, in which dust particles appear at some initial time, are investigated. The obtained results show that the relaxation of plasmas can be accompanied by a deviation of the ion distribution function from equilibrium as well as a change of the mean energy of electrons and ions because of the dependence of the collection of electrons and ions by dust particles on their energy. (author)

  6. Recycling of steelmaking dusts: The Radust concept

    Directory of Open Access Journals (Sweden)

    Jalkanen H.

    2005-01-01

    Full Text Available Recycling of dusts and other wastes of steelmaking is becoming to a necessity of two reasons: due to high contents of iron oxides dusts are valuable raw material for steelmaking and tightening environmental legislation makes the landfill disposal of wastes more expensive. Fine dust fractions from various stages of steelmaking route contain besides iron and carbon heavy metals especially zinc and lead and heavy hydrocarbons that are acceptable neither for landfill disposal nor for recycling back to processes without any spe4cial treatments. Some theoretical and practical aspects concerning high temperature treatments of steelmaking dusts for removal of hazardous components and production of clean high iron raw material for recycling is discussed in this paper. The Radust technology developed at Koverhar steelwork in Finland for treatment of the most problematic fine fractions of blast furnace and oxygen converter dusts is shortly presented and discussed.

  7. Dust storm events over Delhi: verification of dust AOD forecasts with satellite and surface observations

    Science.gov (United States)

    Singh, Aditi; Iyengar, Gopal R.; George, John P.

    2016-05-01

    Thar desert located in northwest part of India is considered as one of the major dust source. Dust storms originate in Thar desert during pre-monsoon season, affects large part of Indo-Gangetic plains. High dust loading causes the deterioration of the ambient air quality and degradation in visibility. Present study focuses on the identification of dust events and verification of the forecast of dust events over Delhi and western part of IG Plains, during the pre-monsoon season of 2015. Three dust events have been identified over Delhi during the study period. For all the selected days, Terra-MODIS AOD at 550 nm are found close to 1.0, while AURA-OMI AI shows high values. Dust AOD forecasts from NCMRWF Unified Model (NCUM) for the three selected dust events are verified against satellite (MODIS) and ground based observations (AERONET). Comparison of observed AODs at 550 nm from MODIS with NCUM predicted AODs reveals that NCUM is able to predict the spatial and temporal distribution of dust AOD, in these cases. Good correlation (~0.67) is obtained between the NCUM predicted dust AODs and location specific observations available from AERONET. Model under-predicted the AODs as compared to the AERONET observations. This may be mainly because the model account for only dust and no anthropogenic activities are considered. The results of the present study emphasize the requirement of more realistic representation of local dust emission in the model both of natural and anthropogenic origin, to improve the forecast of dust from NCUM during the dust events.

  8. Dust Evolution in Galaxy Cluster Simulations

    Science.gov (United States)

    Gjergo, Eda; Granato, Gian Luigi; Murante, Giuseppe; Ragone-Figueroa, Cinthia; Tornatore, Luca; Borgani, Stefano

    2018-06-01

    We implement a state-of-the-art treatment of the processes affecting the production and Interstellar Medium (ISM) evolution of carbonaceous and silicate dust grains within SPH simulations. We trace the dust grain size distribution by means of a two-size approximation. We test our method on zoom-in simulations of four massive (M200 ≥ 3 × 1014M⊙) galaxy clusters. We predict that during the early stages of assembly of the cluster at z ≳ 3, where the star formation activity is at its maximum in our simulations, the proto-cluster regions are rich in dusty gas. Compared to the case in which only dust production in stellar ejecta is active, if we include processes occurring in the cold ISM,the dust content is enhanced by a factor 2 - 3. However, the dust properties in this stage turn out to be significantly different from those observationally derived for the average Milky Way dust, and commonly adopted in calculations of dust reprocessing. We show that these differences may have a strong impact on the predicted spectral energy distributions. At low redshift in star forming regions our model reproduces reasonably well the trend of dust abundances over metallicity as observed in local galaxies. However we under-produce by a factor of 2 to 3 the total dust content of clusters estimated observationally at low redshift, z ≲ 0.5 using IRAS, Planck and Herschel satellites data. This discrepancy does not subsist by assuming a lower sputtering efficiency, which erodes dust grains in the hot Intracluster Medium (ICM).

  9. Dust in the Quasar Wind (Artist Concept)

    Science.gov (United States)

    2007-01-01

    Dusty grains -- including tiny specks of the minerals found in the gemstones peridot, sapphires and rubies -- can be seen blowing in the winds of a quasar, or active black hole, in this artist's concept. The quasar is at the center of a distant galaxy. Astronomers using NASA's Spitzer Space Telescope found evidence that such quasar winds might have forged these dusty particles in the very early universe. The findings are another clue in an ongoing cosmic mystery: where did all the dust in our young universe come from? Dust is crucial for efficient star formation as it allows the giant clouds where stars are born to cool quickly and collapse into new stars. Once a star has formed, dust is also needed to make planets and living creatures. Dust has been seen as far back as when the universe was less than a tenth of its current age, but how did it get there? Most dust in our current epoch forms in the winds of evolved stars that did not exist when the universe was young. Theorists had predicted that winds from quasars growing in the centers of distant galaxies might be a source of this dust. While the environment close to a quasar is too hot for large molecules like dust grains to survive, dust has been found in the cooler, outer regions. Astronomers now have evidence that dust is created in these outer winds. Using Spitzer's infrared spectrograph instrument, scientists found a wealth of dust grains in a quasar called PG2112+059 located at the center of a galaxy 8 billion light-years away. The grains - including corundum (sapphires and rubies); forsterite (peridot); and periclase (naturally occurring in marble) - are not typically found in galaxies without quasars, suggesting they might have been freshly formed in the quasar's winds.

  10. High Latitude Dust in the Earth System

    Science.gov (United States)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; hide

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (> or = 50degN and > or = 40degS) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 sq km and contribute at least 80-100 Tg/yr1 of dust to the Earth system (approx. 5% of the global dust budget); both are projected to increase under future climate change scenarios.

  11. Radiation effluent suppression system

    International Nuclear Information System (INIS)

    Watanabe, Atsushi.

    1992-01-01

    In a radiation release suppression system upon accident, an electromotive valve, a pneumatic operation valve or a manual operation valve is disposed to gas ventilation pipelines which are extended from both of a dry well and a wet well of a reactor container to a stuck. In addition, a combination filter of a metal fiber filter made of stainless steel etc. and an activated carbon fiber filter is disposed in the midway of pipelines in a reactor building. With such a constitution, the inside of the container can be depressurized (prevention of ruptures) and the amount of radioactive substances released to circumstances is remarkably suppressed by the effect of radioactive substance capturing effect of the metal fiber filter made of stainless steel etc. disposed in the vent pipe in the container and a radioactive substance capturing effect by the combination filter of the metal fiber filter made of stainless steel, etc. and the activated carbon fiber filter disposed in the gas ventilation pipelines even upon occurrence of an accident exceeding design basis. Systems can be simplified and minimized, and cost down can also be attained. (N.H.)

  12. Planck-suppressed operators

    International Nuclear Information System (INIS)

    Assassi, Valentin; Baumann, Daniel; Green, Daniel; McAllister, Liam

    2014-01-01

    We show that the recent Planck limits on primordial non-Gaussianity impose strong constraints on light hidden sector fields coupled to the inflaton via operators suppressed by a high mass scale Λ. We study a simple effective field theory in which a hidden sector field is coupled to a shift-symmetric inflaton via arbitrary operators up to dimension five. Self-interactions in the hidden sector lead to non-Gaussianity in the curvature perturbations. To be consistent with the Planck limit on local non-Gaussianity, the coupling to any hidden sector with light fields and natural cubic couplings must be suppressed by a very high scale Λ > 10 5 H. Even if the hidden sector has Gaussian correlations, nonlinearities in the mixing with the inflaton still lead to non-Gaussian curvature perturbations. In this case, the non-Gaussianity is of the equilateral or orthogonal type, and the Planck data requires Λ > 10 2 H

  13. Asian dust events of April 1998

    Science.gov (United States)

    Husar, R.B.; Tratt, D.M.; Schichtel, B.A.; Falke, S.R.; Li, F.; Jaffe, D.; Gasso, S.; Gill, T.; Laulainen, N.S.; Lu, F.; Reheis, M.C.; Chun, Y.; Westphal, D.; Holben, B.N.; Gueymard, C.; McKendry, I.; Kuring, N.; Feldman, G.C.; McClain, C.; Frouin, R.J.; Merrill, J.; DuBois, D.; Vignola, F.; Murayama, T.; Nickovic, S.; Wilson, W.E.; Sassen, K.; Sugimoto, N.; Malm, W.C.

    2001-01-01

    On April 15 and 19, 1998, two intense dust storms were generated over the Gobi desert by springtime low-pressure systems descending from the northwest. The windblown dust was detected and its evolution followed by its yellow color on SeaWiFS satellite images, routine surface-based monitoring, and through serendipitous observations. The April 15 dust cloud was recirculating, and it was removed by a precipitating weather system over east Asia. The April 19 dust cloud crossed the Pacific Ocean in 5 days, subsided to the surface along the mountain ranges between British Columbia and California, and impacted severely the optical and the concentration environments of the region. In east Asia the dust clouds increased the albedo over the cloudless ocean and land by up to 10-20%, but it reduced the near-UV cloud reflectance, causing a yellow coloration of all surfaces. The yellow colored backscattering by the dust eludes a plausible explanation using simple Mie theory with constant refractive index. Over the West Coast the dust layer has increased the spectrally uniform optical depth to about 0.4, reduced the direct solar radiation by 30-40%, doubled the diffuse radiation, and caused a whitish discoloration of the blue sky. On April 29 the average excess surface-level dust aerosol concentration over the valleys of the West Coast was about 20-50 ??g/m3 with local peaks >100 ??g/m3. The dust mass mean diameter was 2-3 ??m, and the dust chemical fingerprints were evident throughout the West Coast and extended to Minnesota. The April 1998 dust event has impacted the surface aerosol concentration 2-4 times more than any other dust event since 1988. The dust events were observed and interpreted by an ad hoc international web-based virtual community. It would be useful to set up a community-supported web-based infrastructure to monitor the global aerosol pattern for such extreme aerosol events, to alert and to inform the interested communities, and to facilitate collaborative

  14. The Spatial Variation of Dust Particulate Matter Concentrations during Two Icelandic Dust Storms in 2015

    Directory of Open Access Journals (Sweden)

    Pavla Dagsson-Waldhauserova

    2016-06-01

    Full Text Available Particulate matter mass concentrations and size fractions of PM1, PM2.5, PM4, PM10, and PM15 measured in transversal horizontal profile of two dust storms in southwestern Iceland are presented. Images from a camera network were used to estimate the visibility and spatial extent of measured dust events. Numerical simulations were used to calculate the total dust flux from the sources as 180,000 and 280,000 tons for each storm. The mean PM15 concentrations inside of the dust plumes varied from 10 to 1600 µg·m−3 (PM10 = 7 to 583 µg·m−3. The mean PM1 concentrations were 97–241 µg·m−3 with a maximum of 261 µg·m−3 for the first storm. The PM1/PM2.5 ratios of >0.9 and PM1/PM10 ratios of 0.34–0.63 show that suspension of volcanic materials in Iceland causes air pollution with extremely high PM1 concentrations, similar to polluted urban areas in Europe or Asia. Icelandic volcanic dust consists of a higher proportion of submicron particles compared to crustal dust. Both dust storms occurred in relatively densely inhabited areas of Iceland. First results on size partitioning of Icelandic dust presented here should challenge health authorities to enhance research in relation to dust and shows the need for public dust warning systems.

  15. Kuiper Belt Dust Grains as a Source of Interplanetary Dust Particles

    Science.gov (United States)

    Liou, Jer-Chyi; Zook, Herbert A.; Dermott, Stanley F.

    1996-01-01

    The recent discovery of the so-called Kuiper belt objects has prompted the idea that these objects produce dust grains that may contribute significantly to the interplanetary dust population. In this paper, the orbital evolution of dust grains, of diameters 1 to 9 microns, that originate in the region of the Kuiper belt is studied by means of direct numerical integration. Gravitational forces of the Sun and planets, solar radiation pressure, as well as Poynting-Robertson drag and solar wind drag are included. The interactions between charged dust grains and solar magnetic field are not considered in the model. Because of the effects of drag forces, small dust grains will spiral toward the Sun once they are released from their large parent bodies. This motion leads dust grains to pass by planets as well as encounter numerous mean motion resonances associated with planets. Our results show that about 80% of the Kuiper belt grains are ejected from the Solar System by the giant planets, while the remaining 20% of the grains evolve all the way to the Sun. Surprisingly, the latter dust grains have small orbital eccentricities and inclinations when they cross the orbit of the Earth. This makes them behave more like asteroidal than cometary-type dust particles. This also enhances their chances of being captured by the Earth and makes them a possible source of the collected interplanetary dust particles; in particular, they represent a possible source that brings primitive/organic materials from the outer Solar System to the Earth. When collisions with interstellar dust grains are considered, however, Kuiper belt dust grains around 9 microns appear likely to be collisionally shattered before they can evolve toward the inner part of the Solar System. The collision destruction can be applied to Kuiper belt grains up to about 50 microns. Therefore, Kuiper belt dust grains within this range may not be a significant part of the interplanetary dust complex in the inner Solar

  16. Health effects from exposure to atmospheric mineral dust near Las Vegas, NV, USA

    Directory of Open Access Journals (Sweden)

    Deborah E. Keil

    Full Text Available Desert areas are usually characterized by a continuous deposition of fine airborne particles. Over time, this process results in the accumulation of silt and clay on desert surfaces. We evaluated health effects associated with regional atmospheric dust, or geogenic dust, deposited on surfaces in the Nellis Dunes Recreation Area (NDRA in Clark County, Nevada, a popular off-road vehicle (ORV recreational site frequented daily by riders, families, and day campers. Because of atmospheric mixing and the mostly regional origin of the accumulated particles, the re-suspended airborne dust is composed of a complex mixture of minerals and metals including aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, arsenic, strontium, cesium, lead, uranium, and others. Geogenic dust with a median diameter of 4.1 μm was administered via oropharyngeal aspiration to female B6C3F1 mice at doses of 0.01 to 100 mg dust/kg body weight, four times, a week apart, for 28-days. Immuno- and neurotoxicological outcomes 24 h following the last exposure were evaluated. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100 mg/kg/day. Splenic and thymic lymphocytic subpopulations and natural killer cell activity also were significantly reduced. Antibodies against MBP, NF-68, and GFAP were not affected, while brain CD3+ T cells were decreased in number. A lowest observed adverse effect level (LOAEL of 0.1 mg/kg/day and a no observed adverse effect level (NOAEL of 0.01 mg/kg/day were derived based on the antigen-specific IgM responses. Keywords: Geogenic dust, Heavy metals, Minerals, Lung exposure, Immunotoxicity, Neurotoxicity

  17. Dust grains from the heart of supernovae

    Science.gov (United States)

    Bocchio, M.; Marassi, S.; Schneider, R.; Bianchi, S.; Limongi, M.; Chieffi, A.

    2016-03-01

    Dust grains are classically thought to form in the winds of asymptotic giant branch (AGB) stars. However, there is increasing evidence today for dust formation in supernovae (SNe). To establish the relative importance of these two classes of stellar sources of dust, it is important to know the fraction of freshly formed dust in SN ejecta that is able to survive the passage of the reverse shock and be injected in the interstellar medium. With this aim, we have developed a new code, GRASH_Rev, that allows following the dynamics of dust grains in the shocked SN ejecta and computing the time evolution of the mass, composition, and size distribution of the grains. We considered four well-studied SNe in the Milky Way and Large Magellanic Cloud: SN 1987A, CasA, the Crab nebula, and N49. These sources have been observed with both Spitzer and Herschel, and the multiwavelength data allow a better assessment the mass of warm and cold dust associated with the ejecta. For each SN, we first identified the best explosion model, using the mass and metallicity of the progenitor star, the mass of 56Ni, the explosion energy, and the circumstellar medium density inferred from the data. We then ran a recently developed dust formation model to compute the properties of freshly formed dust. Starting from these input models, GRASH_Rev self-consistently follows the dynamics of the grains, considering the effects of the forward and reverse shock, and allows predicting the time evolution of the dust mass, composition, and size distribution in the shocked and unshocked regions of the ejecta. All the simulated models aagree well with observations. Our study suggests that SN 1987A is too young for the reverse shock to have affected the dust mass. Hence the observed dust mass of 0.7-0.9 M⊙ in this source can be safely considered as indicative of the mass of freshly formed dust in SN ejecta. Conversely, in the other three SNe, the reverse shock has already destroyed between 10-40% of the

  18. SUPPRESSION OF STAR FORMATION IN NGC 1266

    Energy Technology Data Exchange (ETDEWEB)

    Alatalo, Katherine; Lanz, Lauranne; Bitsakis, Theodoros; Appleton, Philip N.; Ogle, Patrick M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Lacy, Mark; Lonsdale, Carol J. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Nyland, Kristina; Meier, David S. [Physics Department, New Mexico Tech, Socorro, NM 87801 (United States); Cales, Sabrina L. [Department of Astronomy, Faculty of Physical and Mathematical Sciences, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Chang, Philip [Department of Physics, University of Wisconsin—Milwaukee, Milwaukee, WI 53201 (United States); Davis, Timothy A.; De Zeeuw, P. T. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany); Martín, Sergio, E-mail: kalatalo@ipac.caltech.edu [Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, Domaine Universitaire, F-38406 Saint Martin d' Hères (France)

    2015-01-01

    NGC 1266 is a nearby lenticular galaxy that harbors a massive outflow of molecular gas powered by the mechanical energy of an active galactic nucleus (AGN). It has been speculated that such outflows hinder star formation (SF) in their host galaxies, providing a form of feedback to the process of galaxy formation. Previous studies, however, indicated that only jets from extremely rare, high-power quasars or radio galaxies could impart significant feedback on their hosts. Here we present detailed observations of the gas and dust continuum of NGC 1266 at millimeter wavelengths. Our observations show that molecular gas is being driven out of the nuclear region at M-dot {sub out}≈110 M{sub ⊙} yr{sup –1}, of which the vast majority cannot escape the nucleus. Only 2 M {sub ☉} yr{sup –1} is actually capable of escaping the galaxy. Most of the molecular gas that remains is very inefficient at forming stars. The far-infrared emission is dominated by an ultra-compact (≲ 50 pc) source that could either be powered by an AGN or by an ultra-compact starburst. The ratio of the SF surface density (Σ{sub SFR}) to the gas surface density (Σ{sub H{sub 2}}) indicates that SF is suppressed by a factor of ≈50 compared to normal star-forming galaxies if all gas is forming stars, and ≈150 for the outskirt (98%) dense molecular gas if the central region is powered by an ultra-compact starburst. The AGN-driven bulk outflow could account for this extreme suppression by hindering the fragmentation and gravitational collapse necessary to form stars through a process of turbulent injection. This result suggests that even relatively common, low-power AGNs are able to alter the evolution of their host galaxies as their black holes grow onto the M-σ relation.

  19. Dust limit management strategy in tokamaks

    International Nuclear Information System (INIS)

    Rosanvallon, S.; Grisolia, C.; Andrew, P.; Ciattaglia, S.; Delaporte, P.; Douai, D.; Garnier, D.; Gauthier, E.; Gulden, W.; Hong, S.H.; Pitcher, S.; Rodriguez, L.; Taylor, N.; Tesini, A.; Vartanian, S.; Vatry, A.; Wykes, M.

    2009-01-01

    Dust is produced in tokamaks by the interaction between the plasma and the plasma facing components. Dust has not yet been of a major concern in existing tokamaks mainly because the quantity is small and these devices are not nuclear facilities. However, in ITER and in future reactors, it will represent operational and potential safety issues. From a safety point of view, in order to control the potential dust hazard, the current ITER strategy is based on a defense in depth approach designed to provide reliable confinement systems, to avoid failures, and to measure and minimise the dust inventory. In addition, R and D is put in place for optimisation of the proposed methods, such as improvement of measurement, dust cleaning and the reduction of dust production. The aim of this paper is to present the approach for the control of the dust inventory, relying on the monitoring of envelope values and the development of removal techniques already developed in the existing tokamaks or plasma dedicated devices or which will need further research and development in order to be integrated in ITER.

  20. Dust limit management strategy in tokamaks

    Science.gov (United States)

    Rosanvallon, S.; Grisolia, C.; Andrew, P.; Ciattaglia, S.; Delaporte, P.; Douai, D.; Garnier, D.; Gauthier, E.; Gulden, W.; Hong, S. H.; Pitcher, S.; Rodriguez, L.; Taylor, N.; Tesini, A.; Vartanian, S.; Vatry, A.; Wykes, M.

    2009-06-01

    Dust is produced in tokamaks by the interaction between the plasma and the plasma facing components. Dust has not yet been of a major concern in existing tokamaks mainly because the quantity is small and these devices are not nuclear facilities. However, in ITER and in future reactors, it will represent operational and potential safety issues. From a safety point of view, in order to control the potential dust hazard, the current ITER strategy is based on a defense in depth approach designed to provide reliable confinement systems, to avoid failures, and to measure and minimise the dust inventory. In addition, R&D is put in place for optimisation of the proposed methods, such as improvement of measurement, dust cleaning and the reduction of dust production. The aim of this paper is to present the approach for the control of the dust inventory, relying on the monitoring of envelope values and the development of removal techniques already developed in the existing tokamaks or plasma dedicated devices or which will need further research and development in order to be integrated in ITER.

  1. Hypervelocity Dust Injection for Plasma Diagnostic Applications

    Science.gov (United States)

    Ticos, Catalin

    2005-10-01

    Hypervelocity micron-size dust grain injection was proposed for high-temperature magnetized plasma diagnosis. Multiple dust grains are launched simultaneously into high temperature plasmas at several km/s or more. The hypervelocity dust grains are ablated by the electron and ion fluxes. Fast imaging of the resulting luminous plumes attached to each grain is expected to yield local magnetic field vectors. Combination of multiple local magnetic field vectors reproduces 2D or even 3D maps of the internal magnetic field topology. Key features of HDI are: (1) a high spatial resolution, due to a relatively small transverse size of the elongated tail, and (2) a small perturbation level, as the dust grains introduce negligible number of particles compared to the plasma particle inventory. The latter advantage, however, could be seriously compromised if the gas load from the accelerator has an unobstructed access to the diagnosed plasma. Construction of a HDI diagnostic for National Spherical Torus Experiment (NSTX), which includes a coaxial plasma gun for dust grain acceleration, is underway. Hydrogen and deuterium gas discharges inside accelerator are created by a ˜ 1 mF capacitor bank pre-charged up to 10 kV. The diagnostic apparatus also comprises a dust dispenser for pre-loading the accelerator with dust grains, and an imaging system that has a high spatial and temporal resolution.

  2. Testing of a Plasmadynamic Hypervelocity Dust Accelerator

    Science.gov (United States)

    Ticos, Catalin M.; Wang, Zhehui; Dorf, Leonid A.; Wurden, G. A.

    2006-10-01

    A plasmadynamic accelerator for microparticles (or dust grains) has been designed, built and tested at Los Alamos National laboratory. The dust grains are expected to be accelerated to hypervelocities on the order of 1-30 km/s, depending on their size. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10 kV, a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems. The coaxial plasma gun produces a high density (10^18 cm-3) and low temperature (˜ 1 eV) plasma in deuterium ejected by J x B forces, which provides drag on the dust particles in its path. Carbon dust particles will be used, with diameters from 1 to 50 μm. The plasma parameters produced in the coaxial gun are presented and their implication to dust acceleration is discussed. High speed dust will be injected in the National Spherical Torus Experiment to measure the pitch angle of magnetic field lines.

  3. Featured Image: Making Dust in the Lab

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    This remarkable photograph (which spans only 10 m across; click for a full view) reveals what happens when you form dust grains in a laboratory under conditions similar to those of interstellar space. The cosmic life cycle of dust grains is not well understood we know that in the interstellar medium (ISM), dust is destroyed at a higher rate than it is produced by stellar sources. Since the amount of dust in the ISM stays constant, however, there must be additional sources of dust production besides stars. A team of scientists led by Daniele Fulvio (Pontifical Catholic University of Rio de Janeiro and the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena) have now studied formation mechanisms of dust grains in the lab by mimicking low-temperature ISM conditions and exploring how, under these conditions, carbonaceous materials condense from gas phase to form dust grains. To read more about their results and see additional images, check out the paper below.CitationDaniele Fulvio et al 2017 ApJS 233 14. doi:10.3847/1538-4365/aa9224

  4. THE MEASUREMENT AND DISTRIBUTION OF WOOD DUST

    Directory of Open Access Journals (Sweden)

    Andrea Rosario Proto

    2010-03-01

    Full Text Available In Italy, the woodworking industry presents many issues in terms of occupational health and safety. This study on exposure to wood dust could contribute to the realization of a prevention model in order to limit exposure to carcinogenic agents to the worker. The sampling methodology illustrated the analysis of dust emissions from the woodworking machinery in operation throughout the various processing cycles. The quantitative and qualitative assessment of exposure was performed using two different methodologies. The levels of wood dust were determined according to EN indications and sampling was conducted using IOM and Cyclon personal samplers. The qualitative research of wood dust was performed using an advanced laser air particle counter. This allowed the number of particles present to be counted in real time. The results obtained allowed for an accurate assessment of the quality of the dust emitted inside the workplace during the various processing phases. The study highlighted the distribution of air particles within the different size classes, the exact number of both thin and ultra-thin dusts, and confirmed the high concentration of thin dust particles which can be very harmful to humans.

  5. Pebble Bed Reactor Dust Production Model

    Energy Technology Data Exchange (ETDEWEB)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  6. Pebble Bed Reactor Dust Production Model

    International Nuclear Information System (INIS)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-01-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production

  7. Simulation of dust-acoustic waves

    International Nuclear Information System (INIS)

    Winske, D.; Murillo, M.S.; Rosenberg, M.

    1998-01-01

    The authors use molecular dynamics (MD) and particle-in-cell (PIC) simulation methods to investigate the dispersion relation of dust-acoustic waves in a one-dimensional, strongly coupled (Coulomb coupling parameter Λ = ratio of the Coulomb energy to the thermal energy = 120) dusty plasma. They study both cases where the dust is represented by a small number of simulation particles that form into a regular array structure (crystal limit) as well as where the dust is represented by a much larger number of particles (fluid limit)

  8. Backscattering Moessbauer spectroscopy of Martian dust

    International Nuclear Information System (INIS)

    Bertelsen, P.; Madsen, M. B.; Binau, C. S.; Goetz, W.; Gunnlaugsson, H. P.; Hviid, S. F.; Kinch, K. M.; Klingelhoefer, G.; Leer, K.; Madsen, D. E.; Merrison, J.; Olsen, M.; Squyres, S. W.

    2005-01-01

    We report on the determination of the mineralogy of the atmospherically suspended Martian dust particles using backscattering 57 Fe Moessbauer spectroscopy on dust accumulated onto the magnets onboard the Mars Exploration Rovers. The spectra can be interpreted in terms of minerals of igneous origin, and shows only limited, if any, amounts of secondary minerals that may have formed in the presence of liquid water. These findings suggest that the dust has formed in a dry environment over long time in the history of the planet.

  9. Dust and radon: the legal implications

    International Nuclear Information System (INIS)

    Van Sittert, J.M.O.

    1990-01-01

    It is known that radon gas is not generally considered to be a major problem when encountered in the working environment. However, in its process of decay, a series of four short lived daughter products are formed. In a dust-laden atmosphere these daughter products, which are ionized readily, attach to the particulate material and when inhaled are deposited in the alveoli of the lungs. Therefore, if respirable dust is controlled, the effects of radon daughters will also be minimized. The legal requirements for dust control in South Africa and their implications are discussed. 1 ill

  10. Is there dust in galactic haloes

    International Nuclear Information System (INIS)

    Greenberg, J.M.; Ferrini, F.; Pisa Univ.; Barsella, B.; Aiello, S.

    1987-01-01

    The ubiquitous presence of dust within the disks of spiral galaxies is well established. The authors predict that the presence of dust in these regions may be revealed in bright edge-on galaxies, especially by using the polarization of the scattered light from the symmetric lanes. The detection of scattered light above the galactic plane may be an indicator that the parent galaxy has not suffered close encounters with other galaxies at least within the timescale required to establish the dust layers. (author)

  11. Residual dust charges in discharge afterglow

    International Nuclear Information System (INIS)

    Coueedel, L.; Mikikian, M.; Boufendi, L.; Samarian, A. A.

    2006-01-01

    An on-ground measurement of dust-particle residual charges in the afterglow of a dusty plasma was performed in a rf discharge. An upward thermophoretic force was used to balance the gravitational force. It was found that positively charged, negatively charged, and neutral dust particles coexisted for more than 1 min after the discharge was switched off. The mean residual charge for 200-nm-radius particles was measured. The dust particle mean charge is about -5e at a pressure of 1.2 mbar and about -3e at a pressure of 0.4 mbar

  12. Effect of non-Maxwellian particle trapping and dust grain charging on dust acoustic solitary waves

    International Nuclear Information System (INIS)

    Rubab, N.; Murtaza, G.; Mushtaq, A.

    2006-01-01

    The role of adiabatic trapped ions on a small but finite amplitude dust acoustic wave, including the effect of adiabatic dust charge variation, is investigated in an unmagnetized three-component dusty plasma consisting of electrons, ions and massive micron sized negatively charged dust particulates. We have assumed that electrons and ions obey (r,q) velocity distribution while the dust species is treated fluid dynamically. It is found that the dynamics of dust acoustic waves is governed by a modified r dependent Korteweg-de Vries equation. Further, the spectral indices (r,q) affect the charge fluctuation as well as the trapping of electrons and ions and consequently modify the dust acoustic solitary wave

  13. Dust storm detection using random forests and physical-based ...

    Indian Academy of Sciences (India)

    arid areas of the Middle. East. Due to the influences of dust aerosols on climate and human daily activities, dust detection plays a crucial role in environmental and climatic studies. Detection of dust storms is critical to accurately under- stand dust ...

  14. Dust analysis on board the Destiny+ mission to 3200 Phaethon

    Science.gov (United States)

    Krüger, H.; Kobayashi, M.; Arai, T.; Srama, R.; Sarli, B. V.; Kimura, H.; Moragas-Klostermeyer, G.; Soja, R.; Altobelli, N.; Grün, E.

    2017-09-01

    The Japanese Destiny+ spacecraft will be launched to the active asteroid 3200 Phaethon in 2022. Among the proposed core payload is an in-situ dust instrument based on the Cassini Cosmic Dust Analyzer. We use the ESA Interplanetary Meteoroid Engineering Model (IMEM), to study detection conditions and fluences of interplanetary and interstellar dust with a dust analyzer on board Destiny+.

  15. Respirable quartz hazard associated with coal mine roof bolter dust

    International Nuclear Information System (INIS)

    Joy, G.J.; Beck, T.W.; Listak, J.M.

    2010-01-01

    Pneumoconiosis has been reported to be increasing among underground coal miners in the Southern Appalachian Region. The National Institute for Occupational Safety and Health conducted a study to examine the particle size distribution and quartz content of dust generated by the installation of roof bolts in mines. Forty-six bulk samples of roof bolting machine pre-cleaner cyclone dump dust and collector box dust were collected from 26 underground coal mines. Real-time and integrated airborne respirable dust concentrations were measured on 3 mining sections in 2 mines. The real-time airborne dust concentrations profiles were examined to identify any concentration changes that might be associated with pre-cleaner cyclone dust discharge events. The study showed that bolter dust is a potential inhalation hazard due to the fraction of dust less than 10 μm in size, and the quartz content of the dust. The pre-cleaner cyclone dust was significantly larger than the collector box dust, indicating that the pre-cleaner functioned properly in removing the larger dust size fraction from the airstream. However, the pre-cleaner dust still contained a substantial amount of respirable dust. It was concluded that in order to maintain the effectiveness of a roof bolter dust collector, periodic removal of dust is required. Appropriate work procedures and equipment are necessary to minimize exposure during this cleaning task. 13 refs., 3 tabs., 2 figs.

  16. Plasma particle lofting : experimental investigation of dust removal force

    NARCIS (Netherlands)

    Heijmans, L.C.J.; Nijdam, S.

    2015-01-01

    Dust is everywhere. Sometimes it's harmless, but sometimes it needs to be removed. Especially in modern optical machinery, dust control can be of vital importance. In this research we look at dust on a surface. We focus on the behaviour under influence of a plasma. The dust particles will stick to a

  17. Screening for suppression in young children: the Polaroid Suppression test

    NARCIS (Netherlands)

    Pott, J.W.R.; Oosterveen, DK; Van Hof-van Duin, J

    1998-01-01

    Background: Assessment of monocular visual impairment during screening of young children is often hampered by lack of cooperation. Because strabismus, amblyopia, or anisometropia may lead to monocular suppression during binocular viewing conditions, a test was developed to screen far suppression in

  18. The physics of wind-blown sand and dust.

    Science.gov (United States)

    Kok, Jasper F; Parteli, Eric J R; Michaels, Timothy I; Karam, Diana Bou

    2012-10-01

    The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.

  19. Experimental Method for Measuring Dust Load on Surfaces in Rooms

    DEFF Research Database (Denmark)

    Lengweiler, Philip; Nielsen, Peter V.; Moser, Alfred

    A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms, there is a n......A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms......, there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental setup, the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions....

  20. Inactivation of dust mites, dust mite allergen, and mold from carpet.

    Science.gov (United States)

    Ong, Kee-Hean; Lewis, Roger D; Dixit, Anupma; MacDonald, Maureen; Yang, Mingan; Qian, Zhengmin

    2014-01-01

    Carpet is known to be a reservoir for biological contaminants, such as dust mites, dust mite allergen, and mold, if it is not kept clean. The accumulation of these contaminants in carpet might trigger allergies or asthma symptoms in both children and adults. The purpose of this study is to compare methods for removal of dust mites, dust mite allergens, and mold from carpet. Carpets were artificially worn to simulate 1 to 2 years of wear in a four-person household. The worn carpets were inoculated together with a common indoor mold (Cladosporium species) and house dust mites and incubated for 6 weeks to allow time for dust mite growth on the carpet. The carpets were randomly assigned to one of the four treatment groups. Available treatment regimens for controlling carpet contaminants were evaluated through a literature review and experimentation. Four moderately low-hazard, nondestructive methods were selected as treatments: vacuuming, steam-vapor, Neem oil (a natural tree extract), and benzalkonium chloride (a quaternary ammonium compound). Steam vapor treatment demonstrated the greatest dust mite population reduction (p 0.05) for both physical and chemical methods. The steam-vapor treatment effectively killed dust mites and denatured dust mite allergen in the laboratory environment.

  1. Mineralogy of Interplanetary Dust Particles from the Comet Giacobini-Zinner Dust Stream Collections

    Science.gov (United States)

    Nakamura-Messenger, K.; Messenger, S.; Westphal, A. J.; Palma, R. L.

    2015-01-01

    The Draconoid meteor shower, originating from comet 21P/Giacobini-Zinner, is a low-velocity Earth-crossing dust stream that had a peak anticipated flux on Oct. 8, 2012. In response to this prediction, NASA performed dedicated stratospheric dust collections to target interplanetary dust particles (IDPs) from this comet stream on Oct 15-17, 2012 [3]. Twelve dust particles from this targeted collection were allocated to our coordinated analysis team for studies of noble gas (Univ. Minnesota, Minnesota State Univ.), SXRF and Fe-XANES (SSL Berkeley) and mineralogy/isotopes (JSC). Here we report a mineralogical study of 3 IDPs from the Draconoid collection..

  2. Study on the alternative mitigation of cement dust spread by capturing the dust with fogging method

    Science.gov (United States)

    Purwanta, Jaka; Marnoto, Tjukup; Setyono, Prabang; Handono Ramelan, Ari

    2017-12-01

    The existence of a cement plant impact the lives of people around the factory site. For example the air quality, which is polluted by dust. Cement plant has made various efforts to mitigate the generated dust, but there are still alot of dust fly inground either from the cement factory chimneys or transportation. The purpose of this study was to conduct a review of alternative mitigation of the spread of dust around the cement plant. This study uses research methods such as collecting secondary data which includes data of rain density, the average rains duration, wind speed and direction as well as data of dust intensity quality around PT. Semen Gresik (Persero) Tbk.Tuban plant. A soft Wind rose file is used To determine the wind direction propensity models. The impact on the spread of dust into the environment is determined using secondary data monitoring air quality. Results of the study is that the mitigation of dust around the cement plant is influenced by natural factors, such as the tendency of wind direction, rain fall and rainy days, and the rate of dust emission from the chimney. The alternative means proposed is an environmental friendly fogging dust catcher.

  3. The composition of circumstellar and interstellar dust

    NARCIS (Netherlands)

    Tielens, AGGM; Woodward, CE; Biscay, MD; Shull, JM

    2001-01-01

    A large number of solid dust components have been identified through analysis of stardust recovered from meteorites, and analysis of IR observations of circumstellar shells and the interstellar medium. These include graphite, hydrogenated amorphous carbon, diamond, PAHs, silicon-, iron-, and

  4. He Puff System For Dust Detector Upgrade

    International Nuclear Information System (INIS)

    Rais, B.; Skinner, C.H.; Roquemore, A.L.

    2010-01-01

    Local detection of surface dust is needed for the safe operation of next-step magnetic fusion devices such as ITER. An electrostatic dust detector, based on a 5 cm x 5 cm grid of interlocking circuit traces biased to 50 V, has been developed to detect dust on remote surfaces and was successfully tested for the first time on the National Spherical Torus Experiment (NSTX). We report on a helium puff system that clears residual dust from this detector and any incident debris or fibers that might cause a permanent short circuit. The entire surface of the detector was cleared of carbon particles by two consecutive helium puffs delivered by three nozzles of 0.45 mm inside diameter. The optimal configuration was found to be with the nozzles at an angle of 30o with respect to the surface of the detector and a helium backing pressure of 6 bar.

  5. Surface acoustic wave dust deposition monitor

    Science.gov (United States)

    Fasching, G.E.; Smith, N.S. Jr.

    1988-02-12

    A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

  6. Stochastic Models of Molecule Formation on Dust

    Science.gov (United States)

    Charnley, Steven; Wirstroem, Eva

    2011-01-01

    We will present new theoretical models for the formation of molecules on dust. The growth of ice mantles and their layered structure is accounted for and compared directly to observations through simulation of the expected ice absorption spectra

  7. Obliquely propagating dust-density waves

    International Nuclear Information System (INIS)

    Piel, A.; Arp, O.; Klindworth, M.; Melzer, A.

    2008-01-01

    Self-excited dust-density waves are experimentally studied in a dusty plasma under microgravity. Two types of waves are observed: a mode inside the dust volume propagating in the direction of the ion flow and another mode propagating obliquely at the boundary between the dusty plasma and the space charge sheath. The dominance of oblique modes can be described in the frame of a fluid model. It is shown that the results fom the fluid model agree remarkably well with a kinetic electrostatic model of Rosenberg [J. Vac. Sci. Technol. A 14, 631 (1996)]. In the experiment, the instability is quenched by increasing the gas pressure or decreasing the dust density. The critical pressure and dust density are well described by the models

  8. 25 years of dust acoustic waves

    Science.gov (United States)

    Merlino, Robert L.; Merlino

    2014-12-01

    The dust acoustic wave (DAW) was first discussed by P. K. Shukla in May of 1989 at the First Capri Workshop on Dusty Plasmas. In the past 25 years, the subsequent publication of the linear and nonlinear properties of the DAW (Rao, N. N., Shukla, P. K. and Yu, M. Y. 1990 Planet. Space Sci. 38, 543) has generated and sustained a large body of theoretical and experimental research that has clarified the physics of collective effects in dusty plasmas. A unique feature of the DAW is that it can be observed (literally) using laser illumination and high-speed videography, revealing details of wave-particle interactions at an unprecedented single particle level. This paper attempts to review some of the contributions and extensions of dust acoustic wave physics, as well as identify recent findings that illustrate the potential importance of this dust wave in the agglomeration of dust particles.

  9. Coir dust reinforced recycled polypropylene composites

    International Nuclear Information System (INIS)

    Santos, Bianca B. dos; Costa, Marysilvia F. da; Thire, Rossana M. da S.M.

    2015-01-01

    The environmental impacts caused by disposed plastics encourage the search for new alternatives. Recycling polymers leads to the degradation of their mechanical properties, which can be modified by the addition of fillers. In this paper, recycled polypropylene from plastic cups with 2%, 5% and 10% of coir dust were produced with and without the addition of additives. These composites were characterized by tensile tests, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy on the fracture surface. It was verified the effectiveness of the addition of coir dust in improving the elasticity modulus of recycled polypropylene besides the effectiveness of additives used in promoting the adhesion of the powder to the matrix. However, higher levels of coir dust caused the appearance of air bubbles inside the material, which contributed to its embrittlement. The addition of coir dust promoted a decrease in the degree of polypropylene crystallinity. (author)

  10. Surface System Dust Mitigation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will perform a detailed examination of dust mitigation and tolerance strategies for connections and mechanisms to be employed on the lunar...

  11. House dust mite control measures for asthma

    DEFF Research Database (Denmark)

    Gøtzsche, Peter C.; Johansen, Helle Krogh

    2008-01-01

    BACKGROUND: The major allergen in house dust comes from mites. Chemical, physical and combined methods of reducing mite allergen levels are intended to reduce asthma symptoms in people who are sensitive to house dust mites. OBJECTIVES: To assess the effects of reducing exposure to house dust mite...... antigens in the homes of people with mite-sensitive asthma. SEARCH STRATEGY: PubMed and The Cochrane Library (last searches Nov 2007), reference lists. SELECTION CRITERIA: Randomised trials of mite control measures vs placebo or no treatment in people with asthma known to be sensitive to house dust mites......), the standardised mean difference was 0.00 (95% confidence interval (CI) -0.10 to 0.10). There were no statistically significant differences either in number of patients improved (relative risk 1.01, 95% CI 0.80 to 1.27), asthma symptom scores (standardised mean difference -0.04, 95% CI -0.15 to 0...

  12. The Marriage of Gas and Dust

    Science.gov (United States)

    Price, D. J.; Laibe, G.

    2015-10-01

    Dust-gas mixtures are the simplest example of a two fluid mixture. We show that when simulating such mixtures with particles or with particles coupled to grids a problem arises due to the need to resolve a very small length scale when the coupling is strong. Since this is occurs in the limit when the fluids are well coupled, we show how the dust-gas equations can be reformulated to describe a single fluid mixture. The equations are similar to the usual fluid equations supplemented by a diffusion equation for the dust-to-gas ratio or alternatively the dust fraction. This solves a number of numerical problems as well as making the physics clear.

  13. Nanotube Electrodes for Dust Mitigation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Dust mitigation is critical to the survivability of vehicle and infrastructure components and systems and to the safety of astronauts during EVAs and planetary...

  14. Solar-Panel Dust Accumulation and Cleanings

    Science.gov (United States)

    2005-01-01

    Air-fall dust accumulates on the solar panels of NASA's Mars Exploration Rovers, reducing the amount of sunlight reaching the solar arrays. Pre-launch models predicted steady dust accumulation. However, the rovers have been blessed with occasional wind events that clear significant amounts of dust from the solar panels. This graph shows the effects of those panel-cleaning events on the amount of electricity generated by Spirit's solar panels. The horizontal scale is the number of Martian days (sols) after Spirit's Jan. 4, 2005, (Universal Time) landing on Mars. The vertical scale indicates output from the rover's solar panels as a fraction of the amount produced when the clean panels first opened. Note that the gradual declines are interrupted by occasional sharp increases, such as a dust-cleaning event on sol 420.

  15. Investigations of Wind/WAVES Dust Impacts

    Science.gov (United States)

    St Cyr, O. C.; Wilson, L. B., III; Rockcliffe, K.; Mills, A.; Nieves-Chinchilla, T.; Adrian, M. L.; Malaspina, D.

    2017-12-01

    The Wind spacecraft launched in November 1994 with a primary goal to observe and understand the interaction between the solar wind and Earth's magnetosphere. The waveform capture detector, TDS, of the radio and plasma wave investigation, WAVES [Bougeret et al., 1995], onboard Wind incidentally detected micron-sized dust as electric field pulses from the recollection of the impact plasma clouds (an unintended objective). TDS has detected over 100,000 dust impacts spanning almost two solar cycles; a dataset of these impacts has been created and was described in Malaspina & Wilson [2016]. The spacecraft continues to collect data about plasma, energetic particles, and interplanetary dust impacts. Here we report on two investigations recently conducted on the Wind/WAVES TDS database of dust impacts. One possible source of dust particles is the annually-recurring meteor showers. Using the nine major showers defined by the American Meteor Society, we compared dust count rates before, during, and after the peak of the showers using averaging windows of varying duration. However, we found no statistically significant change in the dust count rates due to major meteor showers. This appears to be an expected result since smaller grains, like the micron particles that Wind is sensitive to, are affected by electromagnetic interactions and Poynting-Robertson drag, and so are scattered away from their initial orbits. Larger grains tend to be more gravitationally dominated and stay on the initial trajectory of the parent body so that only the largest dust grains (those that create streaks as they burn up in the atmosphere) are left in the orbit of the parent body. Ragot and Kahler [2003] predicted that coronal mass ejections (CMEs) near the Sun could effectively scatter dust grains of comparable size to those observed by Wind. Thus, we examined the dust count rates immediately before, during, and after the passage of the 350 interplanetary CMEs observed by Wind over its 20+ year

  16. Ice nucleation properties of mineral dusts

    OpenAIRE

    Steinke, Isabelle

    2013-01-01

    Ice nucleation in clouds has a significant impact on the global hydrological cycle as well as on the radiative budget of the Earth. The AIDA cloud chamber was used to investigate the ice nucleation efficiency of various atmospherically relevant mineral dusts. From experiments with Arizona Test Dust (ATD) a humidity and temperature dependent ice nucleation active surface site density parameterization was developed to describe deposition nucleation at temperatures above 220 K. Based...

  17. Ideas about the study of dust

    International Nuclear Information System (INIS)

    Andriesse, C.D.

    1974-01-01

    Agreement seems to exist about the general idea that a dust particle is a tiny piece of solid material, with some atomic lattice and bonding electrons. But questions like: how large are dust particles, what is their chemical composition, how do they scatter and absorb light, are answered differently when different spectral features are discussed. However, observations do give a number of keys for a reasonable particle model. (G.T.H.)

  18. Carbonaceous Components in the Comet Halley Dust

    Science.gov (United States)

    Fomenkova, M. N.; Chang, S.; Mukhin, L. M.

    1994-01-01

    Cometary grains containing large amounts of carbon and/or organic matter (CHON) were discovered by in situ measurements of comet Halley dust composition during VEGA and GIOTTO flyby missions. In this paper, we report the classification of these cometary, grains by means of cluster analysis, discuss the resulting compositional groups, and compare them with substances observed or hypothesized in meteorites, interplanetary dust particles, and the interstellar medium. Grains dominated by carbon and/or organic matter (CHON grains) represent approx. 22% of the total population of measured cometary dust particles. They, usually contain a minor abundance of rock-forming elements as well. Grains having organic material are relatively more abundant in the vicinity of the nucleus than in the outer regions of the coma, which suggests decomposition of the organics in the coma environment. The majority of comet Halley organic particles are multicomponent mixtures of carbon phases and organic compounds. Possibly, the cometary CHON grains may be related to kerogen material of an interstellar origin in carbonaceous meteorites. Pure carbon grains, hydrocarbons and polymers of cyanopolyynes, and multi-carbon monoxides are present in cometary dust as compositionally simple and distinctive components among a variety of others. There is no clear evidence of significant presence of pure formaldehyde or HCN polymers in Halley dust particles. The diversity of types of cometary organic compounds is consistent with the inter-stellar dust model of comets and probably reflects differences in composition of precursor dust. Preservation of this heterogeneity among submicron particles suggest the gentle formation of cometary, nucleus by aggregation of interstellar dust in the protosolar nebula without complete mixing or chemical homogenization at the submicron level.

  19. DIRT: Dust InfraRed Toolbox

    Science.gov (United States)

    Pound, Marc W.; Wolfire, Mark G.; Mundy, Lee G.; Teuben, Peter; Lord, Steve

    2011-02-01

    DIRT is a Java applet for modelling astrophysical processes in circumstellar dust shells around young and evolved stars. With DIRT, you can: select and display over 500,000 pre-run model spectral energy distributions (SEDs) find the best-fit model to your data set account for beam size in model fitting manipulate data and models with an interactive viewer display gas and dust density and temperature profiles display model intensity profiles at various wavelengths

  20. Novel diagnostics for dust in space, Laboratory and fusion plasmas

    International Nuclear Information System (INIS)

    Castaldo, C.

    2011-01-01

    In situ diagnostics for mobile dust, based on dust impact ionization phenomena, as well as silica aerogel dust collectors are discussed for applications to space and fusion plasmas. The feasibility of an electro-optical probe to detect hypervelocity (>1 km/s) dust particles in tokamaks is evaluated. For quiescent plasmas, a diagnostic of submicron dust based on measurements of plasma fluctuation spectra can be used (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Quasar Winds as Dust Factories at High Redshift

    OpenAIRE

    Elvis, Martin; Marengo, Massimo; Karovska, Margarita

    2003-01-01

    Winds from AGN and quasars will form large amounts of dust, as the cool gas in these winds passes through the (pressure, temperature) region where dust is formed in AGB stars. Conditions in the gas are benign to dust at these radii. As a result quasar winds may be a major source of dust at high redshifts, obviating a difficulty with current observations, and requiring far less dust to exist at early epochs.

  2. A GCM Study of Responses of the Atmospheric Water Cycle of West Africa and the Atlantic to Saharan Dust Radiative Forcing

    Science.gov (United States)

    Lau, K. M.; Kim, K. M.; Sud, Y. C.; Walker, G. K.

    2009-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summerr, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are ehanIed over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer overr the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at0

  3. Palaeo-dust records: A window to understanding past environments

    Science.gov (United States)

    Marx, Samuel K.; Kamber, Balz S.; McGowan, Hamish A.; Petherick, Lynda M.; McTainsh, Grant H.; Stromsoe, Nicola; Hooper, James N.; May, Jan-Hendrik

    2018-06-01

    Dust entrainment, transport over vast distances and subsequent deposition is a fundamental part of the Earth system. Yet the role and importance of dust has been underappreciated, due largely to challenges associated with recognising dust in the landscape and interpreting its depositional history. Despite these challenges, interest in dust is growing. Technical advances in remote sensing and modelling have improved understanding of dust sources and production, while advances in sedimentology, mineralogy and geochemistry (in particular) have allowed dust to be more easily distinguished within sedimentary deposits. This has facilitated the reconstruction of records of dust emissions through time. A key advance in our understanding of dust has occurred following the development of methods to geochemically provenance (fingerprint) dust to its source region. This ability has provided new information on dust transport pathways, as well as the reach and impact of dust. It has also expanded our understanding of the processes driving dust emissions over decadal to millennial timescales through linking dust deposits directly to source area conditions. Dust provenance studies have shown that dust emission, transport and deposition are highly sensitive to variability in climate. They also imply that dust emissions are not simply a function of the degree of aridity in source areas, but respond to a more complex array of conditions, including sediment availability. As well as recording natural variability, dust records are also shown to sensitively track the impact of human activity. This is reflected by both changing dust emission rates and changing dust chemistry. Specific examples of how dust responds to, and records change, are provided with our work on dust emissions from Australia, the most arid inhabited continent and the largest dust source in the Southern Hemisphere. These case studies show that Australian dust emissions reflect hydro-climate variability, with

  4. Thermo-Oxidation of Tokamak Carbon Dust

    International Nuclear Information System (INIS)

    J.W. Davis; B.W.N. Fitzpatrick; J.P. Sharpe; A.A. Haasz

    2008-01-01

    The oxidation of dust and flakes collected from the DIII-D tokamak, and various commercial dust specimens, has been measured at 350 C and 2.0 kPa O 2 pressure. Following an initial small mass loss, most of the commercial dust specimens showed very little effect due to O 2 exposure. Similarly, dust collected from underneath DIII-D tiles, which is thought to comprise largely Grafoil(trademark) particulates, also showed little susceptibility to oxidation at this temperature. However, oxidation of the dust collected from tile surfaces has led to ∼ 18% mass loss after 8 hours; thereafter, little change in mass was observed. This suggests that the surface dust includes some components of different composition and/or structure--possibly fragments of codeposited layers. The oxidation of codeposit flakes scraped form DIII-D upper divertor tiles showed an initial 25% loss in mass due to heating in vacuum, and the gradual loss of 30-38% mass during the subsequent 24 hours exposure to O 2 . This behavior is significantly different from that observed for the oxidation of thinner DIII-D codeposit specimens which were still adhered to tile surfaces, and this is thought to be related to the low deuterium content (D/C ∼ 0.03-0.04) of the flakes

  5. Thermo-oxidation of tokamak carbon dust

    International Nuclear Information System (INIS)

    Davis, J.W.; Fitzpatrick, B.W.N.; Sharpe, J.P.; Haasz, A.A.

    2009-01-01

    The oxidation of dust and flakes collected from the DIII-D tokamak, and various commercial dust specimens, has been measured at 350 deg. C and 2.0 kPa O 2 pressure. Following an initial small mass loss, most of the commercial dust specimens showed very little effect due to O 2 exposure. Similarly, dust collected from underneath DIII-D tiles, which is thought to comprise largely Grafoil TM particulates, also showed little susceptibility to oxidation at this temperature. However, oxidation of the dust collected from tile surfaces has led to ∼18% mass loss after 8 h; thereafter, little change in mass was observed. This suggests that the surface dust includes some components of different composition and/or structure - possibly fragments of codeposited layers. The oxidation of codeposit flakes scraped from DIII-D upper divertor tiles showed an initial 25% loss in mass due to heating in vacuum, and the gradual loss of 30-38% mass during the subsequent 24 h exposure to O 2 . The oxidation of these flakes was much slower than that observed for the oxidation of thinner DIII-D codeposit specimens which were still adhered to tile surfaces. This is thought to be related to structural differences.

  6. Lunar Dust Separation for Toxicology Studies

    Science.gov (United States)

    Cooper, Bonnie L.; McKay, D. S.; Riofrio, L. M.; Taylor, L. A.; Gonzalex, C. P.

    2010-01-01

    During the Apollo missions, crewmembers were briefly exposed to dust in the lunar module, brought in after extravehicular activity. When the lunar ascent module returned to micro-gravity, the dust that had settled on the floor now floated into the air, causing eye discomfort and occasional respiratory symptoms. Because our goal is to set an exposure standard for 6 months of episodic exposure to lunar dust for crew on the lunar surface, these brief exposures of a few days are not conclusive. Based on experience with industrial minerals such as sandblasting quartz, an exposure of several months may cause serious damage, while a short exposure may cause none. The detailed characteristics of sub-micrometer lunar dust are only poorly known, and this is the size range of particles that are of greatest concern. We have developed a method for extracting respirable dust (<2.5 micron) from Apollo lunar soils. This method meets stringent requirements that the soil must be kept dry, exposed only to pure nitrogen, and must conserve and recover the maximum amount of both respirable dust and coarser soil. In addition, we have developed a method for grinding coarser lunar soil to produce sufficient respirable soil for animal toxicity testing while preserving the freshly exposed grain surfaces in a pristine state.

  7. The Dust Management Project: Final Report

    Science.gov (United States)

    Hyatt, Mark J.; Straka, Sharon

    2011-01-01

    A return to the Moon to extend human presence, pursue scientific activities, use the Moon to prepare for future human missions to Mars, and expand Earth s economic sphere, will require investment in developing new technologies and capabilities to achieve affordable and sustainable human exploration. From the operational experience gained and lessons learned during the Apollo missions, conducting longterm operations in the lunar environment will be a particular challenge, given the difficulties presented by the unique physical properties and other characteristics of lunar regolith, including dust. The Apollo missions and other lunar explorations have identified significant lunar dust-related problems that will challenge future mission success. Comprised of regolith particles ranging in size from tens of nanometers to microns, lunar dust is a manifestation of the complex interaction of the lunar soil with multiple mechanical, electrical, and gravitational effects. The environmental and anthropogenic factors effecting the perturbation, transport, and deposition of lunar dust must be studied in order to mitigate it s potentially harmful effects on exploration systems and human explorers. The Dust Management Project (DMP) is tasked with the evaluation of lunar dust effects, assessment of the resulting risks, and development of mitigation and management strategies and technologies related to Exploration Systems architectures. To this end, the DMP supports the overall goal of the Exploration Technology Development Program (ETDP) of addressing the relevant high priority technology needs of multiple elements within the Constellation Program (CxP) and sister ETDP projects. Project scope, approach, accomplishments, summary of deliverables, and lessons learned are presented.

  8. Inhalation of road dust by human subjects.

    Science.gov (United States)

    Takishima, T; Nakamura, M; Sasaki, M; Miyano, M; Yamaya, M; Sasaki, H

    1987-11-01

    We measured pneumomagnetic field strength (PMFS) in 42 healthy control subjects living in districts of Northern Japan with low levels of road dust pollution and in 39 healthy subjects living in areas with high levels of road dust pollution. Suspended road dust produced by studded tires increases from 30 micrograms/m3 during the summer season to levels as high as 400 micrograms/m3 during the snow season in the downtown areas of Sendai, Japan. Road dust retained in the lungs, containing 3% iron, was magnetized from the surface of the chest wall, and PMFS was measured. Three to 5 sequential PMFS measurements were made in each subject in March and October of 1984 and 1985, and in March 1986. The PMFS in control subjects in March 1984 was 37 +/- 14 pico-Tesla (mean +/- SD) and did not significantly differ from the PMFS in October 1984 or that in March 1985. In March 1984, the PMFS of the subjects in highly polluted areas was 95 +/- 100 pico-Tesla (mean +/- SD) and was significantly higher than that of control subjects (p less than 0.01) and subsequently decreased in March 1985 and in March 1986, corresponding to a decrease in suspended road dust brought about by a campaign to eliminate the use of studded tires. Our findings suggest that some road dust caused by studded tires is retained in the lungs.

  9. Modeling Respiratory Toxicity of Authentic Lunar Dust

    Science.gov (United States)

    Santana, Patricia A.; James, John T.; Lam, Chiu-Wing

    2010-01-01

    The lunar expeditions of the Apollo operations from the 60 s and early 70 s have generated awareness about lunar dust exposures and their implication towards future lunar explorations. Critical analyses on the reports from the Apollo crew members suggest that lunar dust is a mild respiratory and ocular irritant. Currently, NASA s space toxicology group is functioning with the Lunar Airborne Dust Toxicity Assessment Group (LADTAG) and the National Institute for Occupational Safety and Health (NIOSH) to investigate and examine toxic effects to the respiratory system of rats in order to establish permissible exposure levels (PELs) for human exposure to lunar dust. In collaboration with the space toxicology group, LADTAG and NIOSH the goal of the present research is to analyze dose-response curves from rat exposures seven and twenty-eight days after intrapharyngeal instillations, and model the response using BenchMark Dose Software (BMDS) from the Environmental Protection Agency (EPA). Via this analysis, the relative toxicities of three types of Apollo 14 lunar dust samples and two control dust samples, titanium dioxide (TiO2) and quartz will be determined. This will be executed for several toxicity endpoints such as cell counts and biochemical markers in bronchoaveolar lavage fluid (BALF) harvested from the rats.

  10. Electronic design of air dust concentration gauge

    International Nuclear Information System (INIS)

    Machaj, B.; Strzalkowski, J.; Krawczynska, B.

    1993-01-01

    A new version of isotope dust concentration gauge for monitoring airborne dust pollution of air employs a ready made personal computer as the control and processing unit in the gauge instead of specialized electronics. That solution of the gauge reduces the needed specialized electronics to a simple computer interface coupling the computer to the measuring head. This also reduced electronics of the measuring head itself, i.e. GM detector circuit, power supplies and electronic circuits to switch on/off driving motors. The functioning and operation of the gauge is controlled by the computer program that can be easily modified if needed. The computer program for the gauge enables automatic measurements of dust concentration. Up to fifty measuring cycles can be easily programmed for a day. The results of measurements are presented in the form of data collection, diagram of dust concentration distribution during one day, diagram of dust distribution during 30 successive days or diagram of average dust concentration distribution during a day which may be computed by combining data of the selected number of measurements. Recalibration of the gauge and checking up of the gauge are also carried out under the program control. (author). 6 refs, 9 figs

  11. Control of dust hazards in mines

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, V V

    1981-09-01

    This paper analyzes health hazards associated with air pollution by respirable coal dust which causes pneumoconioses. The following directions in pneumoconioses prevention are discussed: improved protective systems (e.g. respirators), mining schemes optimized from a health hazards point of view, correct determination of the maximum permissible level of respirable dusts, reducing working time. Safety regulations in the USSR on the critical amount of coal dust in the miner respiratory system are insufficient as the 20 g limit is too high and does not guarantee safety. Using regression analysis influence of the factors which cause pneumoconioses is analyzed. This influence is described by an equation which considers the following factors: number of shifts associated with contact of a miner with coal dusts, dust concentration in mine air, amount of air with coal dust being respirated, miner's age, years as miner, coal rank. It is stated that use of the proposed equation (derived by computer calculations) permits the safe working time to be correctly determined considering all factors which cause pneumoconioses.

  12. Radiative transfer in dust clouds

    International Nuclear Information System (INIS)

    Rowan-Robinson, M.; Harris, S.

    1983-01-01

    The infrared emission has been modelled from 85 late-type M stars, essentially all such stars in the AFGL catalogue with substantial circumstellar dust shells and for which adequate observational data are currently available. The dependence of the emergent spectrum on the temperature of the stars, the condensation temperature of the grains, and the density distribution, optical depth and extent of the shell have been investigated. Consistent models for most stars have been found using dirty silicate grains, with an n(r) proportional to r - 2 density distribution and a grain melting temperature of 1000 K. Allowance has been made for the effect of molecular bands. Although these bands have a dramatic effect on the spectrum of late-type stars at visual wavelengths, there is little effect on the infrared emission from the circumstellar shell. All stars in the study except GL 915, VY CMa and NML Cyg are consistent with having spherically symmetric shells. Except for VY CMa and NML Cyg, for which other evidence suggests a disc geometry, the intensity distributions predicted by the models are consistent with interferometric measurements at infrared wavelengths. (author)

  13. Dynamics of interplanetary dust grains

    International Nuclear Information System (INIS)

    Lamy, P.L.

    1975-01-01

    The interaction of spherical grains of various materials-three silicates (quartz, obsidian and andesite), water-ice and iron - whose radii lie in the micronic and submicronic range with the interplanetary medium is solved. This includes: the interaction with the solar radiation field which is solved using Mie scattering theory and taking into account the precise dependence of the optical properties of the five materials upon wavelength; the interaction with the solar wind: corpuscular tangential drag is found to be always important and may even be larger than the Poynting-Robertson drag; the interaction with the interplanetary magnetic field is investigated in terms of a diffusion or random walk through a series of electromagnetic scatterings, leading to a Chapman-Komolgorov equation (i.e., a generalized Liouville equation). Numerical results are presented for these interactions spanning the entire solar system with circularity of elliptical orbits, direct or retrograde, with grains of various materials and sizes and giving -probably for the first time - a clear global picture of the interaction of dust grains with the interplanetary medium. The dynamics of the grains is then investigated using the theory of general perturbations and the numerical integration of trajectories of circum-solar grains

  14. Atmospheric Dust in the Upper Colorado River Basin: Integrated Analysis of Digital Imagery, Total Suspended Particulate, and Meteorological Data

    Science.gov (United States)

    Urban, F. E.; Reynolds, R. L.; Neff, J. C.; Fernandez, D. P.; Reheis, M. C.; Goldstein, H.; Grote, E.; Landry, C.

    2012-12-01

    Improved measurement and observation of dust emission and deposition in the American west would advance understanding of (1) landscape conditions that promote or suppress dust emission, (2) dynamics of dryland and montane ecosystems, (3) premature melting of snow cover that provides critical water supplies, and (4) possible effects of dust on human health. Such understanding can be applied to issues of land management, water-resource management, as well as the safety and well-being of urban and rural inhabitants. We have recently expanded the scope of particulate measurement in the Upper Colorado River basin through the establishment of total-suspended-particulate (TSP) measurement stations located in Utah and Colorado with bi-weekly data (filter) collection, along with protocols for characterizing dust-on-snow (DOS) layers in Colorado mountains. A sub-network of high-resolution digital cameras has been co-located with several of the TSP stations, as well as at other strategic locations. These real-time regional dust-event detection cameras are internet-based and collect digital imagery every 6-15 minutes. Measurements of meteorological conditions to support these collections and observations are provided partly by CLIM-MET stations, four of which were deployed in 1998 in the Canyonlands (Utah) region. These stations provide continuous, near real-time records of the complex interaction of wind, precipitation, vegetation, as well as dust emission and deposition, in different land-use settings. The complementary datasets of dust measurement and observation enable tracking of individual regional dust events. As an example, the first DOS event of water year 2012 (Nov 5, 2011), as documented at Senator Beck Basin, near Silverton, Colorado, was also recorded by the camera at Island-in-the-Sky (200 km to the northwest), as well as in aeolian activity and wind data from the Dugout Ranch CLIM-MET station (170 km to the west-northwest). At these sites, strong winds and the

  15. Pressure suppression device

    International Nuclear Information System (INIS)

    Yoshida, Toyokazu.

    1976-01-01

    Purpose: To provide a pressure suppression device for a gas cooled reactor wherein the coolant is discharged in a reactor building by a loss-of-coolant accident or the like, the increase in the pressure and temperature is controlled and thermal energy of the discharged coolant of high temperature and high pressure can be absorbed. Constitution: A low heat source unit is provided at the upper part in an inner space of a reactor building provided around the reactor, and at the upper part of the low heat source unit a stirring fan for mixing gas within the building, and a low heat source circulating the low heat source through a pipe is connected to the low heat source unit. The low heat source unit is provided with the pipe arranged in a spiral shape at the upper part of the space of the unit, and a large number of fins are provided at the outer surface of the pipe for increasing the transmission area and improve the heat exchange. When the coolant of high temperature and high pressure has been lost in the building, the thermal energy of the coolant is absorbed by the low heat source unit. (Aizawa, K.)

  16. Ecological relationships between xerophilic fungi and house-dust mites (Acarida: Pyroglyphidae).

    Science.gov (United States)

    Lustgraaf, B V D

    1978-01-01

    At. 75 and 80% relative humidity (RH), on a wheat germ flake medium, Aspergillus penicilloides grew abundantly and suppressed the population growth of Dermatophagoides pteronyssiunus. At 71% RH, A. penicilloides grew moderately and was only antagonistic to D. pteronyssinus when the fungus was previously incubated on the medium.On a human dander medium and on mattress dust, A. penicilloides grew moderately at 71% and 75% RH and stimulated the development of D. pteronyssinus populations. Also a moderate growth of Eurotium repens on human dander positively influenced D. pteronyssinus. Wallemia sebi and Penicillium brevicompactum grew slightly or did not grow at all at 75% RH. No effect was observed on D. pteronyssinus.It appears that xerophilic fungi may stimulate, and occasionally may reduce, the growth of house-dust mite populations in the natural environment.

  17. Transport of Mineral Dust and Its Impact on Climate

    Directory of Open Access Journals (Sweden)

    Kerstin Schepanski

    2018-04-01

    Full Text Available Mineral dust plays a pivotal role in the Earth’s system. Dust modulates the global energy budget directly via its interactions with radiation and indirectly via its influence on cloud and precipitation formation processes. Dust is a micro-nutrient and fertilizer for ecosystems due to its mineralogical composition and thus impacts on the global carbon cycle. Hence, dust aerosol is an essential part of weather and climate. Dust suspended in the air is determined by the atmospheric dust cycle: Dust sources and emission processes define the amount of dust entrained into the atmosphere. Atmospheric mixing and circulation carry plumes of dust to remote places. Ultimately, dust particles are removed from the atmosphere by deposition processes such as gravitational settling and rain wash out. During its residence time, dust interacts with and thus modulates the atmosphere resulting into changes such as in surface temperature, wind, clouds, and precipitation rates. There are still uncertainties regarding individual dust interactions and their relevance. Dust modulates key processes that are inevitably influencing the Earth energy budget. Dust transport allows for these interactions and at the same time, the intermittency of dust transport introduces additional fluctuations into a complex and challenging system.

  18. 'Nuisance Dust' - a Case for Recalibration?

    Science.gov (United States)

    Datson, Hugh; Marker, Brian

    2013-04-01

    This paper considers the case for a review and recalibration of limit values and acceptability criteria for 'nuisance dust', a widely encountered but poorly defined and regulated aspect of particulate matter pollution. Specific dust fractions such as PM10 and asbestiforms are well characterised and have limit values enshrined in legislation. National, and international, limit values for acceptable concentrations of PM10 and other fractions of particulate matter have been defined and agreed. In the United Kingdom (UK), these apply to both public and workplace exposures. By contrast, there is no standard definition or universal criteria against which acceptable levels for 'nuisance dust' can be assessed. This has implications for land-use planning and resource utilisation. Without meaningful limit values, inappropriate development might take place too near to residential dwellings or land containing economically important mineral resources may be effectively sterilised. Furthermore, the expression 'nuisance dust' is unhelpful in that 'nuisance' has a specific meaning in environmental law whilst 'nuisance dust' is often taken to mean 'generally visible particulate matter'. As such, it is associated with the social and broader environmental impacts of particulate matter. PM10 concentrations are usually expressed as a mass concentration over time. These can be determined using a range of techniques. While results from different instruments are generally comparable, data obtained from alternative methods for measuring 'nuisance dust' are rarely interchangeable. In the UK, many of the methods typically used are derived from approaches developed under the HMIP (Her Majesty's Inspectorate of Pollution) regime in the 1960s onwards. Typical methods for 'nuisance dust' sampling focus on measurement of dust mass (from the weight of dust collected in an open container over time) or dust soiling (from loss of reflectance and or obscuration of a surface discoloured by dust over

  19. Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: Implications for emission management and human health

    Energy Technology Data Exchange (ETDEWEB)

    Csavina, Janae [Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Taylor, Mark P. [Environmental Science, Faculty of Science, Macquarie University, North Ryde, Sydney, NSW 2109 (Australia); Félix, Omar [Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Rine, Kyle P. [Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721 (United States); Eduardo Sáez, A., E-mail: esaez@email.arizona.edu [Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721 (United States); Betterton, Eric A., E-mail: betterton@atmo.arizona.edu [Department of Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721 (United States)

    2014-09-15

    Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb and other potentially toxic elements. In this work, we show that size-resolved concentrations of As and Pb generally follow a bimodal distribution with the majority of contaminants in the fine size fraction (< 1 μm) around mining activities that include smelting operations at various sites in Australia and Arizona. This evidence suggests that contaminated fine particles (< 1 μm) are the result of vapor condensation and coagulation from smelting operations while coarse particles are most likely the result of windblown dust from contaminated mine tailings and fugitive emissions from crushing and grinding activities. These results on the size distribution of contaminants around mining operations are reported to demonstrate the ubiquitous nature of this phenomenon so that more effective emission management and practices that minimize health risks associated with metal extraction and processing can be developed. - Highlights: • Lead and copper smelting produce significant atmospheric concentrations of lead and arsenic. • Atmospheric lead and arsenic concentrations depend on particle size. • Lead isotopic analysis can be used to assess source of atmospheric contamination from smelters.

  20. Environmentally dependent dust chemistry of a super Asian dust storm in March 2010: observation and simulation

    Science.gov (United States)

    Wang, Qiongzhen; Dong, Xinyi; Fu, Joshua S.; Xu, Jian; Deng, Congrui; Jiang, Yilun; Fu, Qingyan; Lin, Yanfen; Huang, Kan; Zhuang, Guoshun

    2018-03-01

    Near-surface and vertical in situ measurements of atmospheric particles were conducted in Shanghai during 19-23 March 2010 to explore the transport and chemical evolution of dust particles in a super dust storm. An air quality model with optimized physical dust emission scheme and newly implemented dust chemistry was utilized to study the impact of dust chemistry on regional air quality. Two discontinuous dust periods were observed with one traveling over northern China (DS1) and the other passing over the coastal regions of eastern China (DS2). Stronger mixing extents between dust and anthropogenic emissions were found in DS2, reflected by the higher SO2 / PM10 and NO2 / PM10 ratios as well as typical pollution elemental species such as As, Cd, Pb, and Zn. As a result, the concentrations of SO42- and NO3- and the ratio of Ca2+ / Ca were more elevated in DS2 than in DS1 but opposite for the [NH4+] / [SO42-+NO3-] ratio, suggesting the heterogeneous reactions between calcites and acid gases were significantly promoted in DS2 due to the higher level of relative humidity and gaseous pollution precursors. Lidar observation showed a columnar effect on the vertical structure of particle optical properties in DS1 that dust dominantly accounted for ˜ 80-90 % of the total particle extinction from near the ground to ˜ 700 m. In contrast, the dust plumes in DS2 were restrained within lower altitudes while the extinction from spherical particles exhibited a maximum at a high altitude of ˜ 800 m. The model simulation reproduced relatively consistent results with observations that strong impacts of dust heterogeneous reactions on secondary aerosol formation occurred in areas where the anthropogenic emissions were intensive. Compared to the sulfate simulation, the nitrate formation on dust is suggested to be improved in the future modeling efforts.

  1. DUST AND GAS IN THE DISK OF HL TAURI: SURFACE DENSITY, DUST SETTLING, AND DUST-TO-GAS RATIO

    Energy Technology Data Exchange (ETDEWEB)

    Pinte, C.; Ménard, F. [UMI-FCA, CNRS/INSU, France (UMI 3386), and Dept. de Astronomía, Universidad de Chile, Santiago (Chile); Dent, W. R. F.; Hales, A.; Hill, T.; Cortes, P.; Gregorio-Monsalvo, I. de, E-mail: christophe.pinte@obs.ujf-grenoble.fr [Atacama Large Millimeter/Submillimeter Array, Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago (Chile)

    2016-01-01

    The recent ALMA observations of the disk surrounding HL Tau reveal a very complex dust spatial distribution. We present a radiative transfer model accounting for the observed gaps and bright rings as well as radial changes of the emissivity index. We find that the dust density is depleted by at least a factor of 10 in the main gaps compared to the surrounding rings. Ring masses range from 10–100 M{sub ⊕} in dust, and we find that each of the deepest gaps is consistent with the removal of up to 40 M{sub ⊕} of dust. If this material has accumulated into rocky bodies, these would be close to the point of runaway gas accretion. Our model indicates that the outermost ring is depleted in millimeter grains compared to the central rings. This suggests faster grain growth in the central regions and/or radial migration of the larger grains. The morphology of the gaps observed by ALMA—well separated and showing a high degree of contrast with the bright rings over all azimuths—indicates that the millimeter dust disk is geometrically thin (scale height ≈1 AU at 100 AU) and that a large amount of settling of large grains has already occurred. Assuming a standard dust settling model, we find that the observations are consistent with a turbulent viscosity coefficient of a few 10{sup −4}. We estimate the gas/dust ratio in this thin layer to be of the order of 5 if the initial ratio is 100. The HCO{sup +} and CO emission is consistent with gas in Keplerian motion around a 1.7 M{sub ⊙} star at radii from ≤10–120 AU.

  2. Laboratory studies of immersion and deposition mode ice nucleation of ozone aged mineral dust particles

    Directory of Open Access Journals (Sweden)

    Z. A. Kanji

    2013-09-01

    Full Text Available Ice nucleation in the atmosphere is central to the understanding the microphysical properties of mixed-phase and cirrus clouds. Ambient conditions such as temperature (T and relative humidity (RH, as well as aerosol properties such as chemical composition and mixing state play an important role in predicting ice formation in the troposphere. Previous field studies have reported the absence of sulfate and organic compounds on mineral dust ice crystal residuals sampled at mountain top stations or aircraft based measurements despite the long-range transport mineral dust is subjected to. We present laboratory studies of ice nucleation for immersion and deposition mode on ozone aged mineral dust particles for 233 T ns are reported and observed to increase as a function of decreasing temperature. We present first results that demonstrate enhancement of the ice nucleation ability of aged mineral dust particles in both the deposition and immersion mode due to ageing. We also present the first results to show a suppression of heterogeneous ice nucleation activity without the condensation of a coating of (inorganic material. In immersion mode, low ozone exposed Ka particles showed enhanced ice activity requiring a median freezing temperature of 1.5 K warmer than that of untreated Ka, whereas high ozone exposed ATD particles showed suppressed ice nucleation requiring a median freezing temperature of 3 K colder than that of untreated ATD. In deposition mode, low exposure Ka had ice active fractions of an order of magnitude higher than untreated Ka, whereas high ozone exposed ATD had ice active fractions up to a factor of 4 lower than untreated ATD. From our results, we derive and present parameterizations in terms of ns(T that can be used in models to predict ice nuclei concentrations based on available aerosol surface area.

  3. DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J., E-mail: hhwang@cfa.harvard.edu, E-mail: sandrews@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-11-01

    We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S{sub ν}(880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S{sub ν}(880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10{sup 11}(L{sub ☉}) and 4-14 × 10{sup 7}(M{sub ☉}), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution.

  4. Dust Destruction in the ISM: A Re-Evaluation of Dust Lifetimes

    Science.gov (United States)

    Jones, A. P.; Nuth, J. A., III

    2011-01-01

    There is a long-standing conundrum in interstellar dust studies relating to the discrepancy between the time-scales for dust formation from evolved stars and the apparently more rapid destruction in supernova-generated shock waves. Aims. We re-examine some of the key issues relating to dust evolution and processing in the interstellar medium. Methods. We use recent and new constraints from observations, experiments, modelling and theory to re-evaluate dust formation in the interstellar medium (ISM). Results. We find that the discrepancy between the dust formation and destruction time-scales may not be as significant as has previously been assumed because of the very large uncertainties involved. Conclusions. The derived silicate dust lifetime could be compatible with its injection time-scale, given the inherent uncertainties in the dust lifetime calculation. The apparent need to re-form significant quantities of silicate dust in the tenuous interstellar medium may therefore not be a strong requirement. Carbonaceous matter, on the other hand, appears to be rapidly recycled in the ISM and, in contrast to silicates, there are viable mechanisms for its re-formation in the ISM.

  5. CHARACTERIZATION OF THE DUST GENERATED IN THE RECYCLING PROCESS OF THE ELECTRIC ARC FURNACE DUST

    Directory of Open Access Journals (Sweden)

    Fábio Gonçalves Rizz

    2013-10-01

    Full Text Available Electric Arc Furnace Dust (EAFD is a solid waste generated by the production of steel through the Electric Arc Furnace. This waste is labeled dangerous, which motivates studies aiming its recycling. Experiments were made to study a pyrometallurgical process for the recycling of the dust, using the insertion of dust briquettes in molten pig iron in three temperatures. In the briquettes, there were made additions of calcium fluoride in four different concentrations. This paper has the objective to characterize the dust that results from this process, verifying the influence of the temperature and the concentration of calcium fluoride in the briquette in the morphology and chemical composition of the new dust, determining the optimal conditions for the recovery of the zinc content of the dust. This newly generated dust was analyzed in an Scanning Electronic Microscope, used to capture micrographs and chemical composition by EDS. The micrographs show that the temperature and the calcium fluoride concentration interfere in the way the dust particles agglomerate. Chemical analysis points that the higher zinc recuperation occurrs in the experiments at 1500°C with 7% addition of calcium fluoride.

  6. Dust-cyclotron and dust-lower-hybrid modes in self-gravitating ...

    Indian Academy of Sciences (India)

    cantly modifies the dispersion properties of these two electrostatic modes. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring-systems and cometary tails, are briefly mentioned. Keywords. Dusty plasmas; dust-cyclotron waves; dust-lower-hybrid waves.

  7. The flow of interstellar dust through the solar system: the role of dust charging

    International Nuclear Information System (INIS)

    Sterken, V. J.; Altobelli, N.; Schwehm, G.; Kempf, S.; Srama, R.; Strub, P.; Gruen, E.

    2011-01-01

    Interstellar dust can enter the solar system through the relative motion of the Sun with respect to the Local Interstellar Cloud. The trajectories of the dust through the solar system are not only influenced by gravitation and solar radiation pressure forces, but also by the Lorentz forces due to the interaction of the interplanetary magnetic field with the charged dust particles. The interplanetary magnetic field changes on two major time scales: 25 days (solar rotation frequency) and 22 years (solar cycle). The short-term variability averages out for regions that are not too close (>∼2 AU) to the Sun. This interplanetary magnetic field variability causes a time-variability in the interstellar dust densities, that is correlated to the solar cycle.In this work we characterize the flow of interstellar dust through the solar system using simulations of the dust trajectories. We start from the simple case without Lorentz forces, and expand to the full simulation. We pay attention to the different ways of modeling the interplanetary magnetic field, and discuss the influence of the dust parameters on the resulting flow patterns. We also discuss the possibilities of using this modeling for prediction of dust fluxes for different space missions or planets, and we pay attention to where simplified models are justified, and where or when a full simulation, including all forces is necessary. One of the aims of this work is to understand measurements of spacecraft like Ulysses, Cassini and Stardust.

  8. Variations between Dust and Gas in the Diffuse Interstellar Medium. III. Changes in Dust Properties

    Science.gov (United States)

    Reach, William T.; Bernard, Jean-Philippe; Jarrett, Thomas H.; Heiles, Carl

    2017-12-01

    We study infrared emission of 17 isolated, diffuse clouds with masses of order {10}2 {M}ȯ to test the hypothesis that grain property variations cause the apparently low gas-to-dust ratios that have been measured in those clouds. Maps of the clouds were constructed from Wide-field Infrared Survey Explorer (WISE) data and directly compared with the maps of dust optical depth from Planck. The mid-infrared emission per unit dust optical depth has a significant trend toward lower values at higher optical depths. The trend can be quantitatively explained by the extinction of starlight within the clouds. The relative amounts of polycyclic aromatic hydrocarbon and very small grains traced by WISE, compared with large grains tracked by Planck, are consistent with being constant. The temperature of the large grains significantly decreases for clouds with larger dust optical depth; this trend is partially due to dust property variations, but is primarily due to extinction of starlight. We updated the prediction for molecular hydrogen column density, taking into account variations in dust properties, and find it can explain the observed dust optical depth per unit gas column density. Thus, the low gas-to-dust ratios in the clouds are most likely due to “dark gas” that is molecular hydrogen.

  9. DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

    International Nuclear Information System (INIS)

    Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J.

    2013-01-01

    We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S ν (880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S ν (880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10 11 (L ☉ ) and 4-14 × 10 7 (M ☉ ), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution

  10. Electrostatic Dust Detection and Removal for ITER

    International Nuclear Information System (INIS)

    C.H. Skinner; A. Campos; H. Kugel; J. Leisure; A.L. Roquemore; S. Wagner

    2008-01-01

    We present some recent results on two innovative applications of microelectronics technology to dust inventory measurement and dust removal in ITER. A novel device to detect the settling of dust particles on a remote surface has been developed in the laboratory. A circuit board with a grid of two interlocking conductive traces with 25 (micro)m spacing is biased to 30-50 V. Carbon particles landing on the energized grid create a transient short circuit. The current flowing through the short circuit creates a voltage pulse that is recorded by standard nuclear counting electronics and the total number of counts is related to the mass of dust impinging on the grid. The particles typically vaporize in a few seconds restoring the previous voltage standoff. Experience on NSTX however, showed that in a tokamak environment it was still possible for large particles or fibers to remain on the grid causing a long term short circuit. We report on the development of a gas puff system that uses helium to clear such particles. Experiments with varying nozzle designs, backing pressures, puff durations, and exit flow orientations have given an optimal configuration that effectively removes particles from an area up to 25 cm 2 with a single nozzle. In a separate experiment we are developing an advanced circuit grid of three interlocking traces that can generate a miniature electrostatic traveling wave for transporting dust to a suitable exit port. We have fabricated such a 3-pole circuit board with 25 micron insulated traces that operates with voltages up to 200 V. Recent results showed motion of dust particles with the application of only 50 V bias voltage. Such a device could potentially remove dust continuously without dedicated interventions and without loss of machine availability for plasma operations

  11. Dust Combustion Safety Issues for Fusion Applications

    Energy Technology Data Exchange (ETDEWEB)

    L. C. Cadwallader

    2003-05-01

    This report summarizes the results of a safety research task to identify the safety issues and phenomenology of metallic dust fires and explosions that are postulated for fusion experiments. There are a variety of metal dusts that are created by plasma erosion and disruptions within the plasma chamber, as well as normal industrial dusts generated in the more conventional equipment in the balance of plant. For fusion, in-vessel dusts are generally mixtures of several elements; that is, the constituent elements in alloys and the variety of elements used for in-vessel materials. For example, in-vessel dust could be composed of beryllium from a first wall coating, tungsten from a divertor plate, copper from a plasma heating antenna or diagnostic, and perhaps some iron and chromium from the steel vessel wall or titanium and vanadium from the vessel wall. Each of these elements has its own unique combustion characteristics, and mixtures of elements must be evaluated for the mixture’s combustion properties. Issues of particle size, dust temperature, and presence of other combustible materials (i.e., deuterium and tritium) also affect combustion in air. Combustion in other gases has also been investigated to determine if there are safety concerns with “inert” atmospheres, such as nitrogen. Several coolants have also been reviewed to determine if coolant breach into the plasma chamber would enhance the combustion threat; for example, in-vessel steam from a water coolant breach will react with metal dust. The results of this review are presented here.

  12. Reducing dust and allergen exposure in bakeries

    Directory of Open Access Journals (Sweden)

    Howard J Mason

    2017-12-01

    Full Text Available Bakers have a continuing high incidence of occupational allergic asthma. In factory bakeries they are exposed not only to flour dust containing allergens, but also improvers whose ingredients enhance the strength and workability of the dough and its speed of rising. Improvers are flour-based but can contain added soya, fungal or bacterial enzymes that are also allergenic, as well as vegetable oil, calcium sulphate/silicate and organic esters. This study investigated the dustiness of the components used in factory bakeries and whether altering improver ingredients could reduce dust and allergen exposure. A standardised rotating drum test was employed on the individual components, as well as a representative improver and three practicable improver modifications by decreasing calcium sulphate, calcium silicate or increasing oil content. Levels of dust, the allergens wheat flour amylase inhibitor (WAAI and soya trypsin inhibitor (STI were measured in the generated inhalable, thoracic and respirable sized fractions. A “scooping and pouring” workplace simulation was also performed. Initial tests showed that dustiness of several wheat flours was relatively low, and even lower for soya flour, but increased in combination with some other improver components. All three improver modifications generally reduced levels of dust, STI and WAAI, but increasing oil content significantly decreased dust and STI in comparison to the standard improver and those improvers with reduced calcium silicate or sulphate. The simulation demonstrated that increased oil content reduced inhalable levels of gravimetric dust, STI and WAAI. Changing improver formulation, such as increasing oil content of flour by a small amount, may represent a simple, practical method of reducing bakery workers’ exposure to dust and allergens where improvers are used. It may be a useful adjunct to engineering control, changes to work practices and appropriate training in reducing the risk to

  13. Diagnostics of mobile dust in scrape-off layer plasmas

    International Nuclear Information System (INIS)

    Ratynskaia, S; Castaldo, C; Bergsaaker, H; Rudakov, D

    2011-01-01

    Dust production and accumulation pose serious safety and operational implications for the next generation fusion devices. Mobile dust particles can result in core plasma contamination with impurities, and those with high velocities can significantly contribute to the wall erosion. Diagnostics for monitoring dust in tokamaks during plasma discharges are hence important as they can provide information on dust velocity and size, and-in some cases-on dust composition. Such measurements are also valuable as an input for theoretical models of dust dynamics in scrape-off layer plasmas. Existing in situ dust diagnostics, focusing on the range of dust parameters they can detect, are reviewed. Particular attention is paid to the diagnostics which allow us to detect tails of the dust velocity and size distributions, e.g. small and very fast particles. Some of the techniques discussed have been adopted from space-related research and have been shown to be feasible and useful for tokamak applications as well.

  14. The observation of dust behavior in TRIAM-1M

    International Nuclear Information System (INIS)

    Sasaki, K.; Hanada, K.; Nishino, N.; Tokitani, M.; Yoshida, N.; Sato, K.N.; Zushi, H.; Nakamura, K.; Sakamoto, M.; Idei, H.; Hasegawa, M.; Kawasaki, S.; Nakasihma, H.; Higashijima, A.

    2007-01-01

    The observation of dusts in plasmas was carried out by high speed camera in full non-inductive lower hybrid current drive (LHCD) plasma on TRIAM-1M. The velocities of dusts were 10-50 m/s. The number of dust generated per second increased with the discharge duration in the range of 20-57 s. This suggests that a part of dusts were generated from a movable limiter whose the surface temperature increases with the discharge duration. Dusts were coming from various directions even close to the movable limiter. Dusts were collected in the vacuum vessel by use of a kind of cleaner and the composition and the size of dust were examined by Scanning Electron Microscope (SEM). Dust size was several μm and composition was Molybdenum mixed with small amount of elements of stainless metal. The poloidal distribution of the collected mass of dusts was almost uniform

  15. An electrostatic detector for dust measurement on HT-7 tokamak

    International Nuclear Information System (INIS)

    Ling, B.L.; Zhang, X.D.; Ti, A.; Gao, X.

    2007-01-01

    An electrostatic dust detector has been successfully developed to measure dust event in situ and in real time on the HT-7 tokamak. For measuring dust near the edge plasmas and preventing interference of electrons and ions, the shielding plates were designed and installed around the dust detector. The electric signal of dust has been successfully measured during LHCD discharges on HT-7 tokamak. The measured dust signal was in good agreement with bursts appeared on multi-channel H α radiation and on multi-channel ECE diagnostics. Diagnostics of the spectrum and the measurement of impurity emission during dust bursts were studied in detail. It is interesting that there is a delay between dust bursts and CIII line emission. It is observed that the delay time between dust signal and measured CIII line emission is about 0.3 ms in the HT-7 tokamak

  16. Formation and dissociation of dust molecules in dusty plasma

    Science.gov (United States)

    Yan, Jia; Feng, Fan; Liu, Fucheng; Dong, Lifang; He, Yafeng

    2016-09-01

    Dust molecules are observed in a dusty plasma experiment. By using measurements with high spatial resolution, the formation and dissociation of the dust molecules are studied. The ion cloud in the wake of an upper dust grain attracts the lower dust grain nearby. When the interparticle distance between the upper dust grain and the lower one is less than a critical value, the two dust grains would form a dust molecule. The upper dust grain always leads the lower one as they travel. When the interparticle distance between them is larger than the critical value, the dust molecule would dissociate. Project supported by the National Natural Science Foundation of China (Grant Nos. 11205044 and 11405042), the Natural Science Foundation of Hebei Province, China (Grant Nos. A2011201006 and A2012201015), the Research Foundation of Education Bureau of Hebei Province, China (Grant No. Y2012009), the Program for Young Principal Investigators of Hebei Province, China, and the Midwest Universities Comprehensive Strength Promotion Project, China.

  17. Dust coma of Halley comet: measurements with the dust counter and mass analyzer (DUSMA)

    International Nuclear Information System (INIS)

    Simpson, J.A.; Sagdeev, R.Z.; Tuzzolino, A.J.; AN SSSR, Moscow. Inst. Kosmicheskikh Issledovanij)

    1986-01-01

    The paper represents a preliminary report on measurements of spatial and temporal distribution of mass and flows of dust particles coming from comet nucleus performed by means of devices constructed on the new principle of detecting comet dust specks. The device has a high time resolution (∼ 4 μs) in the wide range of mass and dust flows. On the base of a preliminary analysis the following conclusions are drawn: dust coma in quiet state (''Vega-2'') as well as at the presence of considerable emissions (''Vega-1'') manifests the presence of important short-term out-bursts having by time a quasi-periodic structure. Integral mass spectra show flows intensity growth with the decrease of measured mass (which contradicts some theoretical models). Flow levels lie approximately in the region previously determined by ground observations. The coma is extremely dynamic both in space and in time which proves the complex structure of regions of dust emission from the nucleus

  18. Dust storms and their impact on ocean and human health: dust in Earth's atmosphere

    Science.gov (United States)

    Griffin, Dale W.; Kellog, Christina A.

    2004-01-01

    Satellite imagery has greatly influenced our understanding of dust activity on a global scale. A number of different satellites such as NASA's Earth-Probe Total Ozone Mapping Spectrometer (TOMS) and Se-viewing Field-of-view Sensor (SeaWiFS) acquire daily global-scale data used to produce imagery for monitoring dust storm formation and movement. This global-scale imagery has documented the frequent transmission of dust storm-derived soils through Earth's atmosphere and the magnitude of many of these events. While various research projects have been undertaken to understand this normal planetary process, little has been done to address its impact on ocean and human health. This review will address the ability of dust storms to influence marine microbial population densities and transport of soil-associated toxins and pathogenic microorganisms to marine environments. The implications of dust on ocean and human health in this emerging scientific field will be discussed.

  19. A simplified Suomi NPP VIIRS dust detection algorithm

    Science.gov (United States)

    Yang, Yikun; Sun, Lin; Zhu, Jinshan; Wei, Jing; Su, Qinghua; Sun, Wenxiao; Liu, Fangwei; Shu, Meiyan

    2017-11-01

    Due to the complex characteristics of dust and sparse ground-based monitoring stations, dust monitoring is facing severe challenges, especially in dust storm-prone areas. Aim at constructing a high-precision dust storm detection model, a pixel database, consisted of dusts over a variety of typical feature types such as cloud, vegetation, Gobi and ice/snow, was constructed, and their distributions of reflectance and Brightness Temperatures (BT) were analysed, based on which, a new Simplified Dust Detection Algorithm (SDDA) for the Suomi National Polar-Orbiting Partnership Visible infrared Imaging Radiometer (NPP VIIRS) is proposed. NPP VIIRS images covering the northern China and Mongolian regions, where features serious dust storms, were selected to perform the dust detection experiments. The monitoring results were compared with the true colour composite images, and results showed that most of the dust areas can be accurately detected, except for fragmented thin dusts over bright surfaces. The dust ground-based measurements obtained from the Meteorological Information Comprehensive Analysis and Process System (MICAPS) and the Ozone Monitoring Instrument Aerosol Index (OMI AI) products were selected for comparison purposes. Results showed that the dust monitoring results agreed well in the spatial distribution with OMI AI dust products and the MICAPS ground-measured data with an average high accuracy of 83.10%. The SDDA is relatively robust and can realize automatic monitoring for dust storms.

  20. Chemical signatures of urban, open burning and dust transportation in an urban environment- megacity in South Asia

    Science.gov (United States)

    Priyadharshini, B.; Verma, S.

    2016-12-01

    A sub-micron aerosol sampler (SAS) consisting of two parallel stacked filter units (SFU) was deployed at an urban location (Kolkata) to study the sub-micron aerosols (water soluble inorganic ions (WSII) and carbonaceous aerosols (elemental carbon (EC) and organic carbon (OC)) collected over a year (September 2010 to August 2011). Quantification of 10 WSII species using Ion Chromatograph (IC) indicated alkaline nature of aerosols with calcium (Ca2+) being the major neutralizing factor of acidity at the study site. In terms of WSII percentage contribution, the most abundant were crustal species (Ca2+, magnesium (Mg2+) and marine species (chloride (Cl-)), followed by the secondary species sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+) . Ca2+ (fugitive and transported dust) was dominant throughout the study period with K+ concentrations exhibiting seasonality with agricultural residue burning. Further, results of carbonaceous aerosols analyzed using the OC-EC aerosol analyzer following Interagency Monitoring of Protected Visual Environment (IMPROVE) protocol exhibited pronounced seasonality in OC than EC with the overall mean concentration of OC being three folds than EC. Primary organic carbon (POC) and secondary organic carbon concentrations (SOC) estimated using EC tracer method showed 57% (43%) of POC (SOC) from various emission sources. Investigation of OC/EC ratio along with non-sea salt potassium (nss-K+) values revealed influence of season specific anthropogenic activities on both OC and EC concentrations (viz. Open burning (OB)) besides fossil fuel (FF) and biofuel (BF) usage for cooking and heating prevalent over the region. Source apportionment was discerned using positive matrix factorization (PMF) with four major factors (crustal, agricultural, anthropogenic sources and mixed source (crustal + agriculture + anthropogenic) as the primary contributors to the sub-micron aerosols at the study site.

  1. A Dynamic Enhancement With Background Reduction Algorithm: Overview and Application to Satellite-Based Dust Storm Detection

    Science.gov (United States)

    Miller, Steven D.; Bankert, Richard L.; Solbrig, Jeremy E.; Forsythe, John M.; Noh, Yoo-Jeong; Grasso, Lewis D.

    2017-12-01

    This paper describes a Dynamic Enhancement Background Reduction Algorithm (DEBRA) applicable to multispectral satellite imaging radiometers. DEBRA uses ancillary information about the clear-sky background to reduce false detections of atmospheric parameters in complex scenes. Applied here to the detection of lofted dust, DEBRA enlists a surface emissivity database coupled with a climatological database of surface temperature to approximate the clear-sky equivalent signal for selected infrared-based multispectral dust detection tests. This background allows for suppression of false alarms caused by land surface features while retaining some ability to detect dust above those problematic surfaces. The algorithm is applicable to both day and nighttime observations and enables weighted combinations of dust detection tests. The results are provided quantitatively, as a detection confidence factor [0, 1], but are also readily visualized as enhanced imagery. Utilizing the DEBRA confidence factor as a scaling factor in false color red/green/blue imagery enables depiction of the targeted parameter in the context of the local meteorology and topography. In this way, the method holds utility to both automated clients and human analysts alike. Examples of DEBRA performance from notable dust storms and comparisons against other detection methods and independent observations are presented.

  2. Dust formation and ionization in novae

    International Nuclear Information System (INIS)

    Yamamoto, Tetsuo; Sato, Shuji; Nariai, Kyoji.

    1979-01-01

    In order to explain the fact that some novae show the increase of infrared radiation indicating the formation of circumstellar dust grains while some others do not, the theory that the formation of dust in the circumstellar envelope of a nova depends on the intensity of ultraviolet radiation from a central star has been presented. It is known that the central star of a nova emits radiation at nearly constant rate, and its effective temperature rises. It was concluded that the novae with higher emission than a certain value are the poor candidates for dust formation because the whole envelope is ionized before dust is formed. But this conclusion is misleading. The evolution of the ultraviolet radiation emanating from a central star is summarized. The condensation of grains is possible when the partial pressure of the vapor, from which the grains are formed, becomes higher than the saturation vapor pressure. The temperature of grains can be estimated by equating the radiations absorbed and emitted. The grains evaporate if the grain temperature is higher than the condensation temperature. The formation of a Stroemgren sphere in the exploding envelope of a nova is discussed. For the formation of grains, it is necessary that temperature drops below the condensation temperature before the whole envelope is ionized. Hence dust grains do not grow if the grain temperature at a phase is higher than the condensation temperature. (Kako, I.)

  3. Combustible dusts: a serious industrial hazard.

    Science.gov (United States)

    Joseph, Giby

    2007-04-11

    After investigating three fatal explosions in manufacturing plants, the U.S. Chemical Safety and Hazard Investigation Board (CSB) has concluded: The explosive hazard of combustible dust is not well known, and helping industry to understand this hazard is a priority. Prompted by these three incidents in North Carolina, Kentucky and Indiana and the need to increase the hazard awareness, CSB is conducting a study to examine the nature and scope of dust explosion risks in industry and to identify initiatives that may be necessary to more effectively prevent combustible dust fires and explosions. Such initiatives may include regulatory action, voluntary consensus standards, or other measures that could be taken by industry, labor, government, and other parties. A critical task of the dust study is analyzing past incidents to determine the severity of the problem within industry. The analysis is focusing on the number of incidents, injuries and fatalities, industrial sectors affected, and regulatory oversight. This paper presents the preliminary findings from CSBs analysis of combustible dust incidents over the past 25 years. This paper has not been approved by the Board and is published for general informational purposes only. Every effort has been made to accurately present the contents of any Board-approved report mentioned in this paper. Any material in the paper that did not originate in a Board-approved report is solely the responsibility of the authors and does not represent an official finding, conclusion, or position of the Board.

  4. High temperature and dust load in mines

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, V V; Bolonova, L N; Donets, I K; Mukhina, K Sh

    1989-02-01

    Presents results of study of combined load on the human system of heat and dust as encountered in deep coal mines in the Donbass. Groups of coal miners were studied to ascertain the state of their lungs, particularly the presence of free silica, dust, collagen, etc. The sickness records for a number of Donbass mining associations for the past 25 years were analyzed. Multiple regression analysis of the data obtained led to curves relating the number of shifts worked to dust levels, pulmonary ventilation (0.01 and 0.04 m/sup 3//min) and maximum admissible dust concentrations (2, 4, 6 and 10 mg/m/sup 3/). In the 25-35 C temperature range a rise of 1 C is accompanied by increases of 9.9% in dust mass, 15.4% in silica content, 10.7% in mineral impurities and 2.3% in pathomorphological changes in the lungs. An adjustment to the maximum admissible concentration correction coefficient of 10% for every 1 C over 26 C is recommended. 1 ref.

  5. Infrared astronomy and the galactic dust

    International Nuclear Information System (INIS)

    Pecker, J.C.

    1977-01-01

    The existence, in the Galaxy, of small absorbing dust grains has been known for a long time, as they redden the light of stars located behind them, and obscure by amounts which can often even be several magnitudes... In the infrared, where absorption is smaller, one can see through the dust, while at the same time, one can observe the emission of cold dust clouds. After a brief review of technical developments, the reasons for studying the infrared, and the principles of diagnostics, are given. The analysis of the spectral features leads to identification of ice, graphite, and various silicates, as main constituents of the dust. In the fifth section, examples are given of the various sources that one meets when travelling in the Galaxy: protostars, cold and dilute, dense envelopes of young stars (cold or hot), dilute envelopes of not so young stars, and ejected clouds surrounding evolved objects... The simultaneous observation of dust, molecules and atoms, in the same regions, shows that the knowledge of the circumstellar dense regions might be of a great interest, in the study of the origin of life, and of the evolution of the Universe. (Auth.)

  6. Computer tomography of large dust clouds in complex plasmas

    International Nuclear Information System (INIS)

    Killer, Carsten; Himpel, Michael; Melzer, André

    2014-01-01

    The dust density is a central parameter of a dusty plasma. Here, a tomography setup for the determination of the three-dimensionally resolved density distribution of spatially extended dust clouds is presented. The dust clouds consist of micron-sized particles confined in a radio frequency argon plasma, where they fill almost the entire discharge volume. First, a line-of-sight integrated dust density is obtained from extinction measurements, where the incident light from an LED panel is scattered and absorbed by the dust. Performing these extinction measurements from many different angles allows the reconstruction of the 3D dust density distribution, analogous to a computer tomography in medical applications

  7. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    Landsberger, S.; Iskander, F.Y.; Niset, M.; Heydorn, K.

    2002-01-01

    In the past decade there have been many studies to use Compton suppression methods in routine neutron activation analysis as well as in the traditional role of low level gamma ray counting of environmental samples. On a separate path there have been many new PC based software packages that have been developed to enhance photopeak fitting. Although the newer PC based algorithms have had significant improvements, they still suffer from being effectively used in weak gamma ray lines in natural samples or in neutron activated samples that have very high Compton backgrounds. We have completed a series of experiments to show the usefulness of Compton suppression. As well we have shown the pitfalls when using Compton suppression methods for high counting deadtimes as in the case of neutron activated samples. We have also investigated if counting statistics are the same both suppressed and normal modes. Results are presented in four separate experiments. (author)

  8. Pantoea agglomerans: a marvelous bacterium of evil and good.Part I. Deleterious effects: Dust-borne endotoxins and allergens - focus on cotton dust.

    Science.gov (United States)

    Dutkiewicz, Jacek; Mackiewicz, Barbara; Lemieszek, Marta Kinga; Golec, Marcin; Milanowski, Janusz

    2015-01-01

    The ubiquitous Gram-negative bacterium Pantoea agglomerans (synonyms: Enterobacter agglomerans, Erwinia herbicola) is known both as an epiphytic microbe developing on the surface of plants and as an endophytic organism living inside the plants. The bacterium occurs also abundantly in plant and animal products, in the body of arthropods and other animals, in water, soil, dust and air, and occasionally in humans. From the human viewpoint, the role of this organism is ambiguous, both deleterious and beneficial: on one side it causes disorders in people exposed to inhalation of organic dusts and diseases of crops, and on the other side it produces substances effective in the treatment of cancer and other diseases of humans and animals, suppresses the development of various plant pathogens, promotes plant growth, and appears as a potentially efficient biofertilizer and bioremediator. P. agglomerans was identified as a predominant bacterium on cotton plant grown all over the world, usually as an epiphyte, rarely as pathogen. It is particularly numerous on cotton bract after senescence. During processing of cotton in mills, bacteria and their products are released with cotton dust into air and are inhaled by workers, causing respiratory and general disorders, usually defined as byssinosis. The most adverse substance is endotoxin, a heteropolymer macromolecule present in the outermost part of the cell wall, consisting of lipopolysaccharide (LPS) as a major constituent, phospholipids and protein. The numerous experiments carried out in last quarter of XXth century on laboratory animals and human volunteers supported a convincing evidence that the inhaled endotoxin produced by P. agglomerans causes numerous pathologic effects similar to those elicited by cotton dust, such as influx of free lung cells into airways and activation of alveolar macrophages which secrete mediators (prostaglandins, platelet-activating factor, interleukin-1, tumor necrosis factor) that cause

  9. Pantoea agglomerans: a marvelous bacterium of evil and good.Part I. Deleterious effects: Dust-borne endotoxins and allergens – focus on cotton dust

    Directory of Open Access Journals (Sweden)

    Jacek Dutkiewicz

    2015-12-01

    Full Text Available The ubiquitous Gram-negative bacterium Pantoea agglomerans (synonyms: Enterobacter agglomerans, Erwinia herbicola is known both as an epiphytic microbe developing on the surface of plants and as an endophytic organism living inside the plants. The bacterium occurs also abundantly in plant and animal products, in the body of arthropods and other animals, in water, soil, dust and air, and occasionally in humans. From the human viewpoint, the role of this organism is ambiguous, both deleterious and beneficial: on one side it causes disorders in people exposed to inhalation of organic dusts and diseases of crops, and on the other side it produces substances effective in the treatment of cancer and other diseases of humans and animals, suppresses the development of various plant pathogens, promotes plant growth, and appears as a potentially efficient biofertilizer and bioremediator. P. agglomerans was identified as a predominant bacterium on cotton plant grown all over the world, usually as an epiphyte, rarely as pathogen. It is particularly numerous on cotton bract after senescence. During processing of cotton in mills, bacteria and their products are released with cotton dust into air and are inhaled by workers, causing respiratory and general disorders, usually defined as byssinosis. The most adverse substance is endotoxin, a heteropolymer macromolecule present in the outermost part of the cell wall, consisting of lipopolysaccharide (LPS as a major constituent, phospholipids and protein. The numerous experiments carried out in last quarter of XXth century on laboratory animals and human volunteers supported a convincing evidence that the inhaled endotoxin produced by P. agglomerans causes numerous pathologic effects similar to those elicited by cotton dust, such as influx of free lung cells into airways and activation of alveolar macrophages which secrete mediators (prostaglandins, platelet-activating factor, interleukin-1, tumor necrosis factor

  10. Pantoea agglomerans : a marvelous bacterium of evil and good. Part I. Deleterious effects: Dust-borne endotoxins and allergens – focus on cotton dust

    Directory of Open Access Journals (Sweden)

    Jacek Dutkiewicz

    2015-12-01

    Full Text Available The ubiquitous Gram-negative bacterium Pantoea agglomerans (synonyms: Enterobacter agglomerans , Erwinia herbicola is known both as an epiphytic microbe developing on the surface of plants and as an endophytic organism living inside the plants. The bacterium occurs also abundantly in plant and animal products, in the body of arthropods and other animals, in water, soil, dust and air, and occasionally in humans. From the human viewpoint, the role of this organism is ambiguous, both deleterious and beneficial: on one side it causes disorders in people exposed to inhalation of organic dusts and diseases of crops, and on the other side it produces substances effective in the treatment of cancer and other diseases of humans and animals, suppresses the development of various plant pathogens, promotes plant growth, and appears as a potentially efficient biofertilizer and bioremediator. P. agglomerans was identified as a predominant bacterium on cotton plant grown all over the world, usually as an epiphyte, rarely as pathogen. It is particularly numerous on cotton bract after senescence. During processing of cotton in mills, bacteria and their products are released with cotton dust into air and are inhaled by workers, causing respiratory and general disorders, usually defined as byssinosis. The most adverse substance is endotoxin, a heteropolymer macromolecule present in the outermost part of the cell wall, consisting of lipopolysaccharide (LPS as a major constituent, phospholipids and protein. The numerous experiments carried out in last quarter of XXth century on laboratory animals and human volunteers supported a convincing evidence that the inhaled endotoxin produced by P. agglomerans causes numerous pathologic effects similar to those elicited by cotton dust, such as influx of free lung cells into airways and activation of alveolar macrophages which secrete mediators (prostaglandins, platelet-activating factor, interleukin-1, tumor necrosis factor

  11. Maintaining the Background Dust Opacity During Northern Hemisphere Summer Mars Using Wind Stress Based Dust Lifting

    Science.gov (United States)

    Jha, V.; Kahre, M. A.

    2017-12-01

    The Mars atmosphere has low levels of dust during Northern Hemisphere (NH) spring and summer (the non-dusty season) and increased levels during NH autumn and winter (the dusty season). In the absence of regional or global storms, dust devils and local storms maintain a background minimum dust loading during the non-dusty season. While observational surveys and Global Climate Model (GCM) studies suggest that dust devils are likely to be major contributors to the background haze during NH spring and summer, a complete understanding of the relative contribution of dust devils and local dust storms has not yet been achieved. We present preliminary results from an investigation that focuses on the effects of radiatively active water ice clouds on dust lifting processes during these seasons. Water ice clouds are known to affect atmospheric temperatures directly by absorption and emission of thermal infrared radiation and indirectly through dynamical feedbacks. Our goal is to understand how clouds affect the contribution by local (wind stress) dust storms to the background dust haze during NH spring and summer. The primary tool for this work is the NASA Ames Mars GCM, which contains physical parameterizations for a fully interactive dust cycle. Three simulations that included wind stress dust lifting were executed for a period of 5 Martian years: a case that included no cloud formation, a case that included radiatively inert cloud formation and a case that included radiatively active cloud (RAC) formation. Results show that when radiatively active clouds are included, the clouds in the aphelion cloud belt radiatively heat the atmosphere aloft in the tropics (Figure 1). This heating produces a stronger overturning circulation, which in turn produces an enhanced low-level flow in the Hadley cell return branch. The stronger low-level flow drives higher surface stresses and increased dust lifting in those locations. We examine how realistic these simulated results are by

  12. Thyroid suppression test with dextrothyroxine

    International Nuclear Information System (INIS)

    Rosenthal, D.; Fridman, J.; Ribeiro, H.B.

    1978-01-01

    The classic thyroid suppression test with triiodothyronine (l-T 3 ) has been shown to be efficient as an auxiliary method in the diagnosis of thyroid diseases, but should not be performed on elderly patients or on those with heart disease or a tendency to tachycardia. Since these subjects seem able to support a short period of dextro-thyronine (d-T 4 ) feeding, we compared the effect of d-T 4 and l-T 3 on the 24 hours thyroid uptake in euthyroid and hyperthyroid subjects. After basal radio-iodine uptake determination, 99 patients without hyperthyroidism and 27 with Graves' disease were randomly divided in 2 groups; one received 100μg of l-T 3 per day and the other 4 mg of d-T 4 per day, both groups being treated for a period of 10 days. At the end of this suppression period the 24 hours radio-iodine uptake was measured again and the percentual suppression index (S.I.) calculated. Since the comparison of the two groups showed no difference between the suppressive effect of l-T 3 and d-T 4 in euthyroid subjects, while dextro-thyronine, as levo-triiodothyronine, did not suppress the 24 hours uptake of hyperthyroid patients, l-T 3 or d-T 4 can be used interchangeably to test thyroid suppressibility. In the euthyroid subjects the normal range for the post-suppression uptake was 0-17.1% and for the suppression index 54,7.100% [pt

  13. Suppressed Charmed B Decay

    Energy Technology Data Exchange (ETDEWEB)

    Snoek, Hella Leonie [Vrije Univ., Amsterdam (Netherlands)

    2009-06-02

    This thesis describes the measurement of the branching fractions of the suppressed charmed B0 → D*- a0+ decays and the non-resonant B0 → D*- ηπ+ decays in approximately 230 million Υ(4S) → B$\\bar{B}$ events. The data have been collected with the BABAR detector at the PEP-II B factory at the Stanford Linear Accelerator Center in California. Theoretical predictions of the branching fraction of the B0 → D*- a{sub 0}+ decays show large QCD model dependent uncertainties. Non-factorizing terms, in the naive factorization model, that can be calculated by QCD factorizing models have a large impact on the branching fraction of these decay modes. The predictions of the branching fractions are of the order of 10-6. The measurement of the branching fraction gives more insight into the theoretical models. In general a better understanding of QCD models will be necessary to conduct weak interaction physics at the next level. The presence of CP violation in electroweak interactions allows the differentiation between matter and antimatter in the laws of physics. In the Standard Model, CP violation is incorporated in the CKM matrix that describes the weak interaction between quarks. Relations amongst the CKM matrix elements are used to present the two relevant parameters as the apex of a triangle (Unitarity Triangle) in a complex plane. The over-constraining of the CKM triangle by experimental measurements is an important test of the Standard Model. At this moment no stringent direct measurements of the CKM angle γ, one of the interior angles of the Unitarity Triangle, are available. The measurement of the angle γ can be performed using the decays of neutral B mesons. The B0 → D*- a0+ decay is sensitive to the angle γ and, in comparison to the current decays that are being employed, could significantly

  14. Energetics study of West African dust haze

    International Nuclear Information System (INIS)

    Omotosho, J.B.

    1988-10-01

    The causes of the large and often persistent negative anomalies of equivalent potential temperature observed in the 900-700 hpa layer and which occurs in association with dust haze outbreaks over Kano in winter is investigated. Energetics results indicate that the primary mechanism for such anomalies is the horizontal transport of drier and, to a lesser extent, colder air at the upper levels by eddy motions, with consequent destabilization of the atmospheric boundary layer over the station. This is suggested as the mobilization mechanism responsible for raising dust from the surface over the Bilma/Faya-Largeau source region much further poleward. Temperature inversions were also found to be more pronounced during dust spells than in clear periods. (author). 18 refs, 6 figs, 2 tabs

  15. Dust Spectroscopy and the Nature of Grains

    Science.gov (United States)

    Tielens, A. G. G. M.

    2006-01-01

    Ground-based, air-borne and space-based, infrared spectra of a wide variety of objects have revealed prominent absorption and emission features due to large molecules and small dust grains. Analysis of this data reveals a highly diverse interstellar and circumstellar grain inventory, including both amorphous materials and highly crystalline compounds (silicates and carbon). This diversity points towards a wide range of physical and chemical birthsites as well as a complex processing of these grains in the interstellar medium. In this talk, I will review the dust inventory contrasting and comparing both the interstellar and circumstellar reservoirs. The focus will be on the processes that play a role in the lifecycle of dust in the interstellar medium.

  16. Dust grain resonant capture: A statistical study

    Science.gov (United States)

    Marzari, F.; Vanzani, V.; Weidenschilling, S. J.

    1993-01-01

    A statistical approach, based on a large number of simultaneous numerical integrations, is adopted to study the capture in external mean motion resonances with the Earth of micron size dust grains perturbed by solar radiation and wind forces. We explore the dependence of the resonant capture phenomenon on the initial eccentricity e(sub 0) and perihelion argument w(sub 0) of the dust particle orbit. The intensity of both the resonant and dissipative (Poynting-Robertson and wind drag) perturbations strongly depends on the eccentricity of the particle while the perihelion argument determines, for low inclination, the mutual geometrical configuration of the particle's orbit with respect to the Earth's orbit. We present results for three j:j+1 commensurabilities (2:3, 4:5 and 6:7) and also for particle sizes s = 15, 30 microns. This study extends our previous work on the long term orbital evolution of single dust particles trapped into resonances with the Earth.

  17. Absorption and emission characteristics of interstellar dust

    International Nuclear Information System (INIS)

    Allamandola, L.J.

    1984-01-01

    Molecular transitions which occur in the middle infrared region of the spectrum correspond with the characteristic frequencies of molecular vibrations. Thus, moderate resolution spectroscopy of the interstellar medium offers unique evidence about the molecules in the condensed and gaseous phases and their distribution. The author discusses the spectral properties of the condensed phase. However, in the astrophysical literature, it is difficult to find a qualitative description of the effects the solid state has on molecular vibrations, and since it is these which largely determine the spectroscopic properties of the interstellar dust, this discussion begins with a general description of these effects and then is directed toward describing the optical characteristics of the molecular ice component of the dust. The properties of this component of the dust are stressed, rather than those expected from more homogeneous components such as silicates, graphite, or amorphous carbon since these have been discussed in considerable detail elsewhere. (Auth.)

  18. Electrodynamic Dust Shield for Space Applications

    Science.gov (United States)

    Mackey, Paul J.; Johansen, Michael R.; Olsen, Robert C.; Raines, Matthew G.; Phillips, James R., III; Cox, Rachel E.; Hogue, Michael D.; Pollard, Jacob R. S.; Calle, Carlos I.

    2016-01-01

    Dust mitigation technology has been highlighted by NASA and the International Space Exploration Coordination Group (ISECG) as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has developed an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. Further development is underway to improve the operation and reliability of the EDS as well as to perform material and component testing outside of the International Space Station (ISS) on the Materials on International Space Station Experiment (MISSE). This experiment is designed to verify that the EDS can withstand the harsh environment of space and will look to closely replicate the solar environment experienced on the Moon.

  19. Waste and dust utilisation in shaft furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Senk, D.; Babich, A.; Gudenau, H.W. [Rhein Westfal TH Aachen, Aachen (Germany)

    2005-07-01

    Wastes and dusts from steel industry, non-ferrous metallurgy and other branches can be utilised e.g. in agglomeration processes (sintering, pelletising or briquetting) and by injection into shaft furnaces. This paper deals with the second way. Combustion and reduction behaviour of iron- and carbon-rich metallurgical dusts and sludges containing lead, zinc and alkali as well as other wastes with and without pulverised coal (PC) has been studied when injecting into shaft furnaces. Following shaft furnaces have been examined: blast furnace, cupola furnace, OxiCup furnace and imperial-smelting furnace. Investigations have been done at laboratory and industrial scale. Some dusts and wastes under certain conditions can be not only reused but can also improve combustion efficiency at the tuyeres as well as furnace performance and productivity.

  20. Migration of Interplanetary Dust and Comets

    Science.gov (United States)

    Ipatov, S. I.; Mather, J. C.

    Our studies of migration of interplanetary dust and comets were based on the results of integration of the orbital evolution of 15,000 dust particles and 30,000 Jupiter-family comets (JFCs) [1-3]. For asteroidal and cometary particles, the values of the ratio β between the radiation pressure force and the gravitational force varied from 1000 and 1 microns. The probability of a collision of a dust particle started from an asteroid or JFC with the Earth during a lifetime of the particle was maximum at diameter d ˜100 microns. For particles started from asteroids and comet 10P, this maximum probability was ˜0.01. Different studies of migration of dust particles and small bodies testify that the fraction of cometary dust particles of the overall dust population inside Saturn's orbit is considerable and can be dominant: (1) Cometary dust particles produced both inside and outside Jupiter's orbit are needed to explain the observed constant number density of dust particles at 3-18 AU. The number density of migrating trans-Neptunian particles near Jupiter's orbit is smaller by a factor of several than that beyond Saturn's orbit. Only a small fraction of asteroidal particles can get outside Jupiter's orbit. (2) Some (less than 0.1%) JFCs can reach typical near-Earth object orbits and remain there for millions of years. Dynamical lifetimes of most of the former JFCs that have typical near-Earth object orbits are about 106 -109 yr, so during most of these times they were extinct comets. Such former comets could disintegrate and produce a lot of mini-comets and dust. (3) Comparison of the velocities of zodiacal dust particles (velocities of MgI line) based on the distributions of particles over their orbital elements obtained in our runs [3-4] with the velocities obtained at the WHAM observations shows that only asteroidal dust particles cannot explain these observations, and particles produced by comets, including high-eccentricity comets, are needed for such explanation

  1. New methods and standards for fine dust

    International Nuclear Information System (INIS)

    Spielvogel, Juergen; Hartstock, Stefan; Grimm, Hans

    2009-01-01

    There seems to be common agreement that PM10 is a suboptimal quantity for the quantification of potential dangers from fine dust due to a number of reasons, notably because the chemical composition of the particles is not considered, because the size distribution is disregarded, and because of sampling artefacts. In a first step for improving the particle measurements, the European Community has published new directives for ambient air in June 2008 (EU 2008), which as a main part included new regulations for PM2.5 measurements, in addition to the further on valid regulations for PM10. The comparison of PM2.5 and PM10 may allow a source apportionment and a better assessment of the influence of fine dust on human health. The source apportionment may allow more effective fine dust reduction strategies.

  2. The Tranisiting Dust of Boyajian's Star

    Science.gov (United States)

    Bodman, Eva; Ellis, Tyler G.; Boyajian, Tabetha S.; Wright, Jason

    2018-06-01

    From May to October of 2017, Boyajian's Star displayed four days-long dips in observed flux, which are referred to as “Elsie,” “Celeste,” “Skara Brae,” and “Angkor” (Boyajian et al. 2018). This Elsie family dip event was monitored with the Las Cumbres Observatory in three bands, B, r', and i'. Looking at each dip individually, we analyze the multi-band photometry for wavelength dependency in dip depth to constrain properties of the transiting material. We find that all of the dips show non-grey extinction and are consistent with optically thin dust. Interpreting the dips as transiting dust clouds, we constrain the properties of the dust grains and find that the average grain radius is causing the dips is from a separate population.

  3. Dust Studies in DIII-D and TEXTOR

    International Nuclear Information System (INIS)

    Rudakov, D.L.; Litnovsky, A.; West, W.P.; Yu, J.H.; Boedo, J.A.; Bray, B.D.; Brezinsek, S.; Brooks, N.H.; Fenstermacher, M.E.; Groth, M.; Hollmann, E.M.; Huber, A.; Hyatt, A.W.; Krasheninnikov, S.I.; Lasnier, C.J.; Moyer, R.A.; Pigarov, A.Y.; Philipps, V.; Pospieszczyk, A.; Smirnov, R.D.; Sharpe, J.P.; Solomon, W.M.; Watkins, J.G.; Wong, C.C.

    2009-01-01

    Studies of naturally occurring and artificially introduced carbon dust are conducted in DIII-D and TEXTOR. In DIII-D, dust does not present operational concerns except immediately after entry vents. Submicron sized dust is routinely observed using Mie scattering from a Nd:Yag laser. The source is strongly correlated with the presence of Type I edge localized modes (ELMs). Larger size (0.005-1 mm diameter) dust is observed by optical imaging, showing elevated dust levels after entry vents. Inverse dependence of the dust velocity on the inferred dust size is found from the imaging data. Direct heating of the dust particles by the neutral beam injection (NBI) and acceleration of dust particles by the plasma flows are observed. Energetic plasma disruptions produce significant amounts of dust. Large flakes or debris falling into the plasma may result in a disruption. Migration of pre-characterized carbon dust is studied in DIII-D and TEXTOR by introducing micron-size dust in plasma discharges. In DIII-D, a sample holder filled with ∼30 mg of dust is introduced in the lower divertor and exposed to high-power ELMing H-mode discharges with strike points swept across the divertor floor. After a brief exposure (∼0.1 s) at the outer strike point, part of the dust is injected into the plasma, raising the core carbon density by a factor of 2-3 and resulting in a twofold increase of the radiated power. In TEXTOR, instrumented dust holders with 1-45 mg of dust are exposed in the scrape-off layer 0-2 cm radially outside of the last closed flux surface in discharges heated with neutral beam injection (NBI) power of 1.4 MW. At the given configuration of the launch, the dust did not penetrate the core plasma and only moderately perturbed the edge plasma, as evidenced by an increase of the edge carbon content.

  4. A SUBMILLIMETER CONTINUUM SURVEY OF LOCAL DUST-OBSCURED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Chul [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of); Hwang, Ho Seong [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 02455 (Korea, Republic of); Lee, Gwang-Ho, E-mail: jclee@kasi.re.kr [Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2016-12-20

    We conduct a 350 μ m dust continuum emission survey of 17 dust-obscured galaxies (DOGs) at z = 0.05–0.08 with the Caltech Submillimeter Observatory (CSO). We detect 14 DOGs with S{sub 350μm} = 114–650 mJy and signal-to-noise > 3. By including two additional DOGs with submillimeter data in the literature, we are able to study dust content for a sample of 16 local DOGs, which consist of 12 bump and four power-law types. We determine their physical parameters with a two-component modified blackbody function model. The derived dust temperatures are in the range 57–122 K and 22–35 K for the warm and cold dust components, respectively. The total dust mass and the mass fraction of the warm dust component are 3–34 × 10{sup 7} M {sub ⊙} and 0.03%–2.52%, respectively. We compare these results with those of other submillimeter-detected infrared luminous galaxies. The bump DOGs, the majority of the DOG sample, show similar distributions of dust temperatures and total dust mass to the comparison sample. The power-law DOGs show a hint of smaller dust masses than other samples, but need to be tested with a larger sample. These findings support that the reason DOGs show heavy dust obscuration is not an overall amount of dust content, but probably the spatial distribution of dust therein.

  5. A SUBMILLIMETER CONTINUUM SURVEY OF LOCAL DUST-OBSCURED GALAXIES

    International Nuclear Information System (INIS)

    Lee, Jong Chul; Hwang, Ho Seong; Lee, Gwang-Ho

    2016-01-01

    We conduct a 350 μ m dust continuum emission survey of 17 dust-obscured galaxies (DOGs) at z = 0.05–0.08 with the Caltech Submillimeter Observatory (CSO). We detect 14 DOGs with S 350μm = 114–650 mJy and signal-to-noise > 3. By including two additional DOGs with submillimeter data in the literature, we are able to study dust content for a sample of 16 local DOGs, which consist of 12 bump and four power-law types. We determine their physical parameters with a two-component modified blackbody function model. The derived dust temperatures are in the range 57–122 K and 22–35 K for the warm and cold dust components, respectively. The total dust mass and the mass fraction of the warm dust component are 3–34 × 10 7 M ⊙ and 0.03%–2.52%, respectively. We compare these results with those of other submillimeter-detected infrared luminous galaxies. The bump DOGs, the majority of the DOG sample, show similar distributions of dust temperatures and total dust mass to the comparison sample. The power-law DOGs show a hint of smaller dust masses than other samples, but need to be tested with a larger sample. These findings support that the reason DOGs show heavy dust obscuration is not an overall amount of dust content, but probably the spatial distribution of dust therein.

  6. Identifying sources of aeolian mineral dust: Present and past

    Science.gov (United States)

    Muhs, Daniel R; Prospero, Joseph M; Baddock, Matthew C; Gill, Thomas E

    2014-01-01

    Aeolian mineral dust is an important component of the Earth’s environmental systems, playing roles in the planetary radiation balance, as a source of fertilizer for biota in both terrestrial and marine realms and as an archive for understanding atmospheric circulation and paleoclimate in the geologic past. Crucial to understanding all of these roles of dust is the identification of dust sources. Here we review the methods used to identify dust sources active at present and in the past. Contemporary dust sources, produced by both glaciogenic and non-glaciogenic processes, can be readily identified by the use of Earth-orbiting satellites. These data show that present dust sources are concentrated in a global dust belt that encompasses large topographic basins in low-latitude arid and semiarid regions. Geomorphic studies indicate that specific point sources for dust in this zone include dry or ephemeral lakes, intermittent stream courses, dune fields, and some bedrock surfaces. Back-trajectory analyses are also used to identify dust sources, through modeling of wind fields and the movement of air parcels over periods of several days. Identification of dust sources from the past requires novel approaches that are part of the geologic toolbox of provenance studies. Identification of most dust sources of the past requires the use of physical, mineralogical, geochemical, and isotopic analyses of dust deposits. Physical properties include systematic spatial changes in dust deposit thickness and particle size away from a source. Mineralogy and geochemistry can pinpoint dust sources by clay mineral ratios and Sc-Th-La abundances, respectively. The most commonly used isotopic methods utilize isotopes of Nd, Sr, and Pb and have been applied extensively in dust archives of deep-sea cores, ice cores, and loess. All these methods have shown that dust sources have changed over time, with far more abundant dust supplies existing during glacial periods. Greater dust supplies in

  7. Creation of Wood Dust during Wood Processing: Size Analysis, Dust Separation, and Occupational Health

    Directory of Open Access Journals (Sweden)

    Eva Mračková

    2015-11-01

    Full Text Available Mechanical separators and fabric filters are being used to remove airborne fine particles generated during the processing and handling of wood. Such particles might have a harmful effect on employee health, not only in small- but also in large-scale wood processing facilities. The amount of wood dust and its dispersion conditions vary according to geometric boundary conditions. Thus, the dispersion conditions could be changed by changing the linear size of the particles. Moreover, the smaller the particles are, the more harmful they can be. It is necessary to become familiar with properties, from a health point of view, of wood dust generated from processing. Wood dust has to be sucked away from the processing area. The fractional separation efficiency of wood dust can be improved using exhaust and filtering devices. Filtration efficiency depends on moisture content, particle size, and device performance. Because of the carcinogenicity of wood dust, the concentration of wood dust in air has to be monitored regularly. Based on the results hereof, a conclusion can be made that both mechanical separators of types SEA and SEB as well as the fabric filters with FINET PES 1 textile are suitable for the separation of wet saw dust from all types of wooden waste produced within the process.

  8. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    Science.gov (United States)

    Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

    2013-08-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

  9. Dust exposure and pneumoconiosis in a South African pottery. 1. Study objectives and dust exposure.

    Science.gov (United States)

    Rees, D; Cronje, R; du Toit, R S

    1992-07-01

    Dust exposure and pneumoconiosis were investigated in a South African pottery that manufactured wall tiles and bathroom fittings. This paper describes the objectives of the investigation and presents dust measurement data. x Ray diffraction showed that the clays used by the pottery had a high quartz content (range 58%-23%, mean 38%). Exposure to respirable dust was measured for 43 workers and was highest (6.6 mg/m3) in a bathroom fitting fettler. Quartz concentrations in excess of 0.1 mg/m3 were found in all sections of the manufacturing process from slip production to biscuit firing and sorting. The proportion of quartz in the respirable dust of these sections was 24% to 33%. This is higher than is usually reported in English potteries. Four hundred and six (80%) of the 509 workers employed at the pottery were potentially at risk of occupational lung disease. The finding of large numbers of pottery workers exposed to unacceptable dust concentrations is not surprising as poor dust control was found in all six wall tile and sanitary ware factories surveyed by the National Centre for Occupational Health between 1973 and 1989. Dust related occupational disease can be expected in potters for many years to come.

  10. Mineral dust transport toward Hurricane Helene (2006)

    Science.gov (United States)

    Schwendike, Juliane; Jones, Sarah C.; Vogel, Bernhard; Vogel, Heike

    2016-05-01

    This study investigates the transport of mineral dust from its source regions in West Africa toward the developing tropical cyclone Helene (2006) and diagnoses the resulting properties of the air influencing the tropical cyclonegenesis. The model system COSMO-ART (Consortium for Small-Scale Modelling-Aerosols and Reactive Trace gases) in which the emission and transport of mineral dust as well as the radiation feedback are taken into account, was used. The emission of mineral dust between 9 and 14 September 2006 occurred in association with the relatively strong monsoon flow and northeasterly trade winds, with gust fronts of convective systems over land, and with the Atlantic inflow. Additionally, increased surface wind speed was linked to orographical effects at the Algerian Mountains, Atlas Mountains, and the Hoggar. The dust, as part of the Saharan air layer, is transported at low levels by the monsoon flow, the Harmattan, the northeasterly trade winds, and the monsoon trough, and is transported upward in the convergence zone between Harmattan and monsoon flow, in the baroclinic zone along the West African coastline, and by convection. At around 700 hPa the dust is transported by the African easterly jet. Dry and dust-free air is found to the north-northwest of the developing tropical depression due to descent in an anticyclone. Based on the model data, it was possible to distinguish between dry (from the anticyclone), dry and dusty (from the Harmattan and northeasterly trade winds), and dusty and moist air (from the monsoon flow and in the tropical depression due to convection).

  11. Experimental Study of Dust Grain Charging

    Science.gov (United States)

    Spann, James F; Venturini, Catherine C.; Comfort, Richard H.; Mian, Abbas M.

    1999-01-01

    The results of an experimental study of the charging mechanisms of micron size dust grains are presented. Individual dust grains are electrodynamically suspended and exposed to an electron beam of known energy and flux, and to far ultraviolet radiation of known wavelength and intensity. Changes in the charge-to-mass ratio of the grain are directly measured as a function of incident beam (electron and/or photon), grain size and composition. Comparisons of our results to theoretical models that predict the grain response are presented.

  12. Dust-Firing of Straw and Additives

    DEFF Research Database (Denmark)

    Wu, Hao; Glarborg, Peter; Frandsen, Flemming

    2011-01-01

    In the present work, the ash chemistry and deposition behavior during straw dust-firing were studied by performing experiments in an entrained flow reactor. The effect of using spent bleaching earth (SBE) as an additive in straw combustion was also investigated by comparing with kaolinite. During...... dust-firing of straw, the large (>∼2.5 μm) fly ash particles generated were primarily molten or partially molten spherical particles rich in K, Si, and Ca, supplemented by Si-rich flake-shaped particles. The smaller fly ash particles (...

  13. Risk of dust explosions of combustible nanomaterials

    International Nuclear Information System (INIS)

    Dobashi, Ritsu

    2009-01-01

    Nanomaterials have several valuable properties and are widely used for various practical applications. However, safety matters are suspected such as the influence on health and environment, and fire and explosion hazards. To minimize the risk of nanomaterials, appropriate understanding of these hazards is indispensable. Nanoparticles of combustible materials have potential hazard of dust explosion accidents. However, the explosion risk of nanomaterials has not yet been understood adequately because of the lack of data for nanomaterials. In this presentation, the risk of dust explosions of nanomaterials is discussed.

  14. Activation analysis of deposited dust brought to Israel by dust storms

    International Nuclear Information System (INIS)

    Ganor, E.; Tal, A.; Donagi, A.

    1975-01-01

    The determination of dust particles deposited in Jerusalem during regional dust storms was carried out by polarized microscopy, X-ray analysis and atomic absorption measurements. These analyses showed the presence of particles of quartz, calcite, dolomite, feldspar, halite, kaolinite, montmorillonite, epidote, tourmaline, glauconite, illite and other heavy minerals. The aims of the present study were to apply activation analysis for the determination of element composition in dust samples; to compare the results obtained by activation analysis with those obtained by other methods, i.e. chemical analysis, polarized microscopy and X-ray analysis. The results obtained by the various methods were in good agreement. (B.G.)

  15. INFRARED LUMINOSITIES AND DUST PROPERTIES OF z ∼ 2 DUST-OBSCURED GALAXIES

    International Nuclear Information System (INIS)

    Bussmann, R. S.; Dey, Arjun; Jannuzi, B. T.; Borys, C.; Desai, V.; Sheth, K.; Soifer, B. T.; Le Floc'h, E.; Melbourne, J.

    2009-01-01

    We present SHARC-II 350 μm imaging of twelve 24 μm bright (F 24μm > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Booetes field of the NOAO Deep Wide-Field Survey. Detections of four DOGs at 350 μm imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm-dust spectral energy distribution (SED) scaled to the observed 24 μm flux density. The 350 μm upper limits for the 8 non-detected DOGs are consistent with both Mrk 231 and M82 (warm-dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1 mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ∼3 x 10 8 M sun . In comparison to other dusty z ∼ 2 galaxy populations such as submillimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2 x 10 13 L sun versus 6 x 10 12 L sun for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K versus ∼30 K) and lower inferred dust masses (3 x 10 8 M sun versus 3 x 10 9 M sun ). Wide-field Herschel and Submillimeter Common-User Bolometer Array-2 surveys should be able to detect hundreds of these power-law-dominated DOGs. We use the existing Hubble Space Telescope and Spitzer/InfraRed Array Camera data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24 μm bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z ∼ 2 involves a submillimeter bright, cold-dust, and star

  16. Dust-gas interaction deduced from Halley multicolour camera observations

    International Nuclear Information System (INIS)

    Huebner, W.F.; Delamere, W.A.; Keller, H.U.; Reitsema, H.J.; Schmidt, H.U.; Whipple, F.L.; Wilhelm, K.

    1986-01-01

    The dust and gas productions of Comet Halley were measured by the dust counter and the mass spectrometers on the Giotto spacecraft. These instruments give only little information about the spatial asymmetry of the activity. The asymmetry in the dust production is clearly evident from the dust jets seen in the Halley Multicolour Camera images. Since the dust is entrained by the gas, production must be similarly asymmetric. The intensity profiles along and across several dust jets are related to their source regions on the nucleus. Properties of the dust jets are investigated. A few compact, but highly active source regions on the nucleus produce most of the visible dust and can account for most of the gas produced by the comet. 2 refs

  17. Dust removal from waste gas arising from fluidized beds

    International Nuclear Information System (INIS)

    Soltys, L.

    1992-01-01

    Two types dust removal equipment mostly useful for dust removal from waste gas from fluidized beds, i.e. electrofilters and pulsatory bag filters were presented. Their features and functional properties were compared. (author). 7 refs, 4 figs

  18. Optimising a fall out dust monitoring sampling programme at a ...

    African Journals Online (AJOL)

    GREG

    Key words: Fall out dust monitoring, cement plant, optimising, air pollution sampling, fall out dust sampler locations. .... applied for those areas where controls are in place. Sampling ..... mass balance in the total cement manufacturing process.

  19. Ozone Production by Colliding Dust in the Martian Atmosphere

    Science.gov (United States)

    Baragiola, R. A.; Dukes, C. A.

    2012-03-01

    Laboratory studies show that ozone is produced by electrical discharges when rocks fracture. We propose that a similar process should occur in the collision of dust particles during dust storms in Mars and discuss implications.

  20. Arabian Red Sea coastal soils as potential mineral dust sources

    KAUST Repository

    Prakash, P. Jish; Stenchikov, Georgiy L.; Tao, Weichun; Yapici, Tahir; Warsama, Bashir H.; Engelbrecht, Johann

    2016-01-01

    , because of its proximity, directly affects the Red Sea and coastal urban centers. The potential of soils to be suspended as airborne mineral dust depends largely on soil texture, moisture content and particle size distributions. Airborne dust inevitably

  1. The Impact of Mars Atmospheric Dust on Human Health

    Science.gov (United States)

    Kamakolanu, U. G.

    2017-06-01

    The martian dust impact can be considered as an exposure to ultra fine particles of martian dust. Direct nose to brain pathway of particulate matter can affect the fine motor skills and gross motor skills, cognition may be affected.

  2. Dust in Snow in the Colorado River Basin: Spatial Variability in Dust Concentrations, Radiative Forcing, and Snowmelt Rates

    Science.gov (United States)

    Skiles, M.; Painter, T.; Deems, J. S.; Landry, C.; Bryant, A.

    2012-12-01

    Since the disturbance of the western US that began with the Anglo settlement in the mid 19th century, the mountain snow cover of the Colorado River Basin (CRB) has been subject to five-fold greater dust loading. This dust deposition accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. We have previously quantified the impacts of dust in snow using a 6-year record of dust concentration and energy balance fluxes at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. Dust loading exhibited interannual variability, and end of year dust concentrations were not necessarily related to the number of dust deposition events. Radiative forcing enhanced springtime melt by 21 to 51 days with the magnitude of advanced loss being linearly related to total dust concentration at the end of snow cover. To expand our understanding of dust on snow deposition patterns we utilize collections of dust concentration at the Colorado Dust on Snow (CODOS) study sites, established in 2009 along the western side of the CRB, to assess spatial variability in dust loading. In situ sampling of dust stratigraphy and concentration occurs twice each season, once over peak snow water equivalent (15 April), and again during melt (15 May). Dust loading occurs at all sites; dust concentrations are always higher in May, vary between sites, and the highest and lowest dust years were 2009 and 2012, respectively. In the absence of regular sampling and energy balance instrumentation these sites do not allow us to quantify the advanced melt due to dust. To facilitate this a new energy balance site, Grand Mesa Study plot (GMSP), was established for water year 2010 in west central Colorado, 150 km north of SBBSA. Back trajectories indicate similar Colorado Plateau dust sources at both SBBSA and GMSP, yet GMSP exhibits slightly lower dust

  3. Optical and microphysical properties of natural mineral dust and anthropogenic soil dust near dust source regions over northwestern China

    Science.gov (United States)

    Wang, Xin; Wen, Hui; Shi, Jinsen; Bi, Jianrong; Huang, Zhongwei; Zhang, Beidou; Zhou, Tian; Fu, Kaiqi; Chen, Quanliang; Xin, Jinyuan

    2018-02-01

    Mineral dust aerosols (MDs) not only influence the climate by scattering and absorbing solar radiation but also modify cloud properties and change the ecosystem. From 3 April to 16 May 2014, a ground-based mobile laboratory was deployed to measure the optical and microphysical properties of MDs near dust source regions in Wuwei, Zhangye, and Dunhuang (in chronological order) along the Hexi Corridor over northwestern China. Throughout this dust campaign, the hourly averaged (±standard deviation) aerosol scattering coefficients (σsp, 550 nm) of the particulates with aerodynamic diameters less than 2.5 µm (PM2.5) at these three sites were sequentially 101.5 ± 36.8, 182.2 ± 433.1, and 54.0 ± 32.0 Mm-1. Correspondingly, the absorption coefficients (σap, 637 nm) were 9.7 ± 6.1, 6.0 ± 4.6, and 2.3 ± 0.9 Mm-1; single-scattering albedos (ω, 637 nm) were 0.902 ± 0.025, 0.931 ± 0.037, and 0.949 ± 0.020; and scattering Ångström exponents (Åsp, 450-700 nm) of PM2.5 were 1.28 ± 0.27, 0.77 ± 0.51, and 0.52 ± 0.31. During a severe dust storm in Zhangye (i.e., from 23 to 25 April), the highest values of σsp2.5 ( ˜ 5074 Mm-1), backscattering coefficient (σbsp2.5, ˜ 522 Mm-1), and ω637 ( ˜ 0.993) and the lowest values of backscattering fraction (b2.5, ˜ 0.101) at 550 nm and Åsp2.5 ( ˜ -0.046) at 450-700 nm, with peak values of aerosol number size distribution (appearing at the particle diameter range of 1-3 µm), exhibited that the atmospheric aerosols were dominated by coarse-mode dust aerosols. It is hypothesized that the relatively higher values of mass scattering efficiency during floating dust episodes in Wuwei and Zhangye are attributed to the anthropogenic soil dust produced by agricultural cultivations.

  4. Lunar Airborne Dust Toxicity Hazard Assessments (Invited)

    Science.gov (United States)

    Cooper, B. L.; McKay, D. S.; Taylor, L. A.; Wallace, W. T.; James, J.; Riofrio, L.; Gonzalez, C. P.

    2009-12-01

    The Lunar Airborne Dust Toxicity Assessment Group (LADTAG) is developing data to set the permissible limits for human exposure to lunar dust. This standard will guide the design of airlocks and ports for EVA, as well as the requirements for filtering and monitoring the atmosphere in habitable vehicles, rovers and other modules. LADTAG’s recommendation for permissible exposure limits will be delivered to the Constellation Program in late 2010. The current worst-case exposure limit of 0.05 mg/m3, estimated by LADTAG in 2006, reflects the concern that lunar dust may be as toxic as quartz dust. Freshly-ground quartz is known to be more toxic than un-ground quartz dust. Our research has shown that the surfaces of lunar soil grains can be more readily activated by grinding than quartz. Activation was measured by the amount of free radicals generated—activated simulants generate Reactive Oxygen Species (ROS) i.e., production of hydroxyl free radicals. Of the various influences in the lunar environment, micrometeorite bombardment probably creates the most long-lasting reactivity on the surfaces of grains, although solar wind impingement and short-wavelength UV radiation also contribute. The comminution process creates fractured surfaces with unsatisfied bonds. When these grains are inhaled and carried into the lungs, they will react with lung surfactant and cells, potentially causing tissue damage and disease. Tests on lunar simulants have shown that dissolution and leaching of metals can occur when the grains are exposed to water—the primary component of lung fluid. However, simulants may behave differently than actual lunar soils. Rodent toxicity testing will be done using the respirable fraction of actual lunar soils (particles with physical size of less than 2.5 micrometers). We are currently separating the fine material from the coarser material that comprises >95% of the mass of each soil sample. Dry sieving is not practical in this size range, so a new system

  5. Nonlinear periodic waves in dusty plasma with variable dust charge

    International Nuclear Information System (INIS)

    Yadav, Lakhan Lal; Bharuthram, R.

    2002-01-01

    Using the reductive perturbation method, we present a theory of nonlinear periodic waves, viz. the cnoidal waves, in a dusty plasma consisting of electrons, ions, and cold dust grains with charge fluctuations, which in the limiting case reduce to dust acoustic solitons. It is found that the frequency of the dust acoustic cnoidal wave increases with its amplitude. The dust charge fluctuations are found to affect the characteristics of the cnoidal waves

  6. RR Tel: Determination of Dust Properties During Minimum Obscuration

    Directory of Open Access Journals (Sweden)

    Jurkić T.

    2012-06-01

    Full Text Available the ISO infrared spectra and the SAAO long-term JHKL photometry of RR Tel in the epochs during minimum obscuration are studied in order to construct a circumstellar dust model. the spectral energy distribution in the near- and the mid-IR spectral range (1–15 μm was obtained for an epoch without the pronounced dust obscuration. the DUSTY code was used to solve the radiative transfer through the dust and to determine the circumstellar dust properties of the inner dust regions around the Mira component. Dust temperature, maximum grain size, dust density distribution, mass-loss rate, terminal wind velocity and optical depth are determined. the spectral energy distribution and the long-term JHKL photometry during an epoch of minimum obscuration show almost unattenuated stellar source and strong dust emission which cannot be explained by a single dust shell model. We propose a two-component model consisting of an optically thin circmustellar dust shell and optically thick dust outside the line of sight in some kind of a flattened geometry, which is responsible for most of the observed dust thermal emission.

  7. Three-Component Dust Models for Interstellar Extinction C ...

    Indian Academy of Sciences (India)

    without standard' method were used to constrain the dust characteristics in the mean ISM (RV = 3.1), ... Interstellar dust models have evolved as the observational data have advanced, and the most popular dust ... distribution comes from the IRAS observation which shows an excess of 12 μ and. 25 μ emission from the ISM ...

  8. Dust: Small-scale processes with global consequences

    Science.gov (United States)

    Okin, G.S.; Bullard, J.E.; Reynolds, R.L.; Ballantine, J.-A.C.; Schepanski, K.; Todd, M.C.; Belnap, J.; Baddock, M.C.; Gill, T.E.; Miller, M.E.

    2011-01-01

    Desert dust, both modern and ancient, is a critical component of the Earth system. Atmospheric dust has important effects on climate by changing the atmospheric radiation budget, while deposited dust influences biogeochemical cycles in the oceans and on land. Dust deposited on snow and ice decreases its albedo, allowing more light to be trapped at the surface, thus increasing the rate of melt and influencing energy budgets and river discharge. In the human realm, dust contributes to the transport of allergens and pathogens and when inhaled can cause or aggravate respiratory diseases. Dust storms also represent a significant hazard to road and air travel. Because it affects so many Earth processes, dust is studied from a variety of perspectives and at multiple scales, with various disciplines examining emissions for different purposes using disparate strategies. Thus, the range of objectives in studying dust, as well as experimental approaches and results, has not yet been systematically integrated. Key research questions surrounding the production and sources of dust could benefit from improved collaboration among different research communities. These questions involve the origins of dust, factors that influence dust production and emission, and methods through which dust can be monitored. ?? Author(s) 2011.

  9. Dust emission: small-scale processes with global consequences

    Science.gov (United States)

    Okin, Gregory S.; Bullard, Joanna E.; Reynolds, Richard L.; Ballantine, John-Andrew C.; Schepanski, Kerstin; Todd, Martin C.; Belnap, Jayne; Baddock, Matthew C.; Gill, Thomas E.; Miller, Mark E.

    2011-01-01

    Desert dust, both modern and ancient, is a critical component of the Earth system. Atmospheric dust has important effects on climate by changing the atmospheric radiation budget, while deposited dust influences biogeochemical cycles in the oceans and on land. Dust deposited on snow and ice decreases its albedo, allowing more light to be trapped at the surface, thus increasing the rate of melt and influencing energy budgets and river discharge. In the human realm, dust contributes to the transport of allergens and pathogens and when inhaled can cause or aggravate respiratory diseases. Dust storms also represent a significant hazard to road and air travel. Because it affects so many Earth processes, dust is studied from a variety of perspectives and at multiple scales, with various disciplines examining emissions for different purposes using disparate strategies. Thus, the range of objectives in studying dust, as well as experimental approaches and results, has not yet been systematically integrated. Key research questions surrounding the production and sources of dust could benefit from improved collaboration among different research communities. These questions involve the origins of dust, factors that influence dust production and emission, and methods through which dust can be monitored.

  10. Effects of grain dust on lungs prior to and following dust remediation.

    Science.gov (United States)

    Pahwa, Punam; Dosman, James A; McDuffie, Helen H

    2008-12-01

    To determine longitudinal estimates of pulmonary function decline in Canadian grain elevator workers before and after dust control by analyzing data collected from five regions of Canada over 15 years. Declines in forced expired volume in one second and forced vital capacity before and after dust control were estimated by using a generalized estimating equations approach. For grain workers who were in the grain industry for 20 or more years both before and after dust control: the mean annual loss of forced expired volume in one second was greatest among current smoking grain workers followed by ex-smokers and nonsmokers, respectively. Similar results were obtained for forced vital capacity. Grain dust control was effective in reducing decline in the lung function measurements among grain workers in all smoking and exposure categories.

  11. Origin of Harmattan dust settled in Northern Ghana – Long transported or local dust?

    DEFF Research Database (Denmark)

    Lyngsie, Gry; Awadzi, Theodore W; Breuning-Madsen, Henrik

    2011-01-01

    is that the majority of dust deposited in northern Ghana may not be from the original Harmattan source in the Bodélé Depression. The aim of this study is therefore to investigate the origin of deposited dust in Tamale, Ghana. This is examined by comparing wind data, grain size distribution, mineralogical......The Harmattan is a dry, dust-laden continental wind which has its origin in the Bodélé Depression in the Chad basin. In Ghana the Harmattan can be experienced from November to March, when the Harmattan replaces the dominant south westerly maritime Monsoon wind. The hypothesis of this study...... and geochemical data from dust samples deposited during the Harmattan and Monsoon seasons, and topsoil. This study shows that despite a clear difference between the wind directions in the Harmattan and Monsoon seasons in Tamale, northern Ghana, no distinct differences are observed between the mineral or elemental...

  12. THREE-DIMENSIONAL DUST MAPPING REVEALS THAT ORION FORMS PART OF A LARGE RING OF DUST

    International Nuclear Information System (INIS)

    Schlafly, E. F.; Rix, H.-W.; Martin, N. F.; Green, G.; Finkbeiner, D. P.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.; Draper, P. W.; Metcalfe, N.; Price, P. A.

    2015-01-01

    The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the three-dimensional distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using this technique, revealing a large (100 pc, 14° diameter), previously unrecognized ring of dust, which we term the ''Orion dust ring''. The ring includes Orion A and B, and is not coincident with current Hα features. The circular morphology suggests formation as an ancient bubble in the interstellar medium, though we have not been able to conclusively identify the source of the bubble. This hint at the history of Orion may have important consequences for models of high-mass star formation and triggered star formation

  13. Simulation study of spheroidal dust gains charging: Applicable to dust grain alignment

    International Nuclear Information System (INIS)

    Zahed, H.; Sobhanian, S.; Mahmoodi, J.; Khorram, S.

    2006-01-01

    The charging process of nonspherical dust grains in an unmagnetized plasma as well as in the presence of a magnetic field is studied. It is shown that unlike the spherical dust grain, due to nonhomogeneity of charge distribution on the spheroidal dust surface, the resultant electric forces on electrons and ions are different. This process produces some surface charge density gradient on the nonspherical grain surface. Effects of a magnetic field and other plasma parameters on the properties of the dust particulate are studied. It has been shown that the alignment direction could be changed or even reversed with the magnetic field and plasma parameters. Finally, the charge distribution on the spheroidal grain surface is studied for different ambient parameters including plasma temperature, neutral collision frequency, and the magnitude of the magnetic field

  14. Bioleaching of metals from WEEE shredding dust.

    Science.gov (United States)

    Marra, Alessandra; Cesaro, Alessandra; Rene, Eldon R; Belgiorno, Vincenzo; Lens, Piet N L

    2018-03-15

    A bioleaching process developed in two separate steps was investigated for the recovery of base metals, precious metals and rare earth elements from dusts generated by Waste Electrical and Electronic Equipment (WEEE) shredding. In the first step, base metals were almost completely leached from the dust in 8 days by Acidithiobacillus thiooxidans (DSM 9463) that lowered the pH of the leaching solution from 3.5 to 1.0. During this step, cerium, europium and neodymium were mobilized at high percentages (>99%), whereas lanthanum and yttrium reached an extraction yield of 80%. In the second step, the cyanide producing Pseudomonas putida WSC361 mobilized 48% of gold within 3 h from the A. thiooxidans leached shredding dust. This work demonstrated the potential application of biohydrometallurgy for resource recovery from WEEE shredding dust, destined to landfill disposal, and its effectiveness in the extraction of valuable substances, including elements at high supply risk as rare earths. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Dust in Protoplanetary Disks: Properties and Evolution

    NARCIS (Netherlands)

    Natta, A.; Testi, L.; Calvet, N.; Henning, T.; Waters, R.; Wilner, D.

    2007-01-01

    We review the properties of dust in protoplanetary disks around optically visible pre-main-sequence stars obtained with a variety of observational techniques, from measurements of scattered light at visual and infrared wavelengths to mid-infrared spectroscopy and millimeter interferometry. A general

  16. IONIZATION AND DUST CHARGING IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Ivlev, A. V.; Caselli, P. [Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching (Germany); Akimkin, V. V., E-mail: ivlev@mpe.mpg.de [Institute of Astronomy of the Russian Academy of Sciences, Pyatnitskaya Street 48, 119017 Moscow (Russian Federation)

    2016-12-10

    Ionization–recombination balance in dense interstellar and circumstellar environments is a key factor for a variety of important physical processes, such as chemical reactions, dust charging and coagulation, coupling of the gas with magnetic field, and development of instabilities in protoplanetary disks. We determine a critical gas density above which the recombination of electrons and ions on the grain surface dominates over the gas-phase recombination. For this regime, we present a self-consistent analytical model, which allows us to calculate exactly the abundances of charged species in dusty gas, without making assumptions on the grain charge distribution. To demonstrate the importance of the proposed approach, we check whether the conventional approximation of low grain charges is valid for typical protoplanetary disks, and discuss the implications for dust coagulation and development of the “dead zone” in the disk. The presented model is applicable for arbitrary grain-size distributions and, for given dust properties and conditions of the disk, has only one free parameter—the effective mass of the ions, shown to have a small effect on the results. The model can be easily included in numerical simulations following the dust evolution in dense molecular clouds and protoplanetary disks.

  17. Cyclo nic separation of uranate dust

    International Nuclear Information System (INIS)

    Nadal, P.

    1976-01-01

    Size of particles of uranate dust which can be entrained by hot gases leaving a multiple-hearth furnace is determined. The convenience of the installation of a cyclone is discussed considering power of the fume-extractor and pressure-drop permissible in the system. (Author)

  18. Heliotropic dust rings for Earth climate engineering

    Science.gov (United States)

    Bewick, R.; Lücking, C.; Colombo, C.; Sanchez, J. P.; McInnes, C. R.

    2013-04-01

    This paper examines the concept of a Sun-pointing elliptical Earth ring comprised of dust grains to offset global warming. A new family of non-Keplerian periodic orbits, under the effects of solar radiation pressure and the Earth's J2 oblateness perturbation, is used to increase the lifetime of the passive cloud of particles and, thus, increase the efficiency of this geoengineering strategy. An analytical model is used to predict the orbit evolution of the dust ring due to solar-radiation pressure and the J2 effect. The attenuation of the solar radiation can then be calculated from the ring model. In comparison to circular orbits, eccentric orbits yield a more stable environment for small grain sizes and therefore achieve higher efficiencies when the orbit decay of the material is considered. Moreover, the novel orbital dynamics experienced by high area-to-mass ratio objects, influenced by solar radiation pressure and the J2 effect, ensure the ring will maintain a permanent heliotropic shape, with dust spending the largest portion of time on the Sun facing side of the orbit. It is envisaged that small dust grains can be released from a circular generator orbit with an initial impulse to enter an eccentric orbit with Sun-facing apogee. Finally, a lowest estimate of 1 × 1012 kg of material is computed as the total mass required to offset the effects of global warming.

  19. Computer simulation of dust grain evolution

    Science.gov (United States)

    Liffman, K.

    1989-01-01

    The latest results are reported from a Monte Carlo code that is being developed at NASA Ames. The goal of this program, is to derive from the observed and presumed properties of the interstellar medium (ISM) the following information: (1) the size spectrum of interstellar dust; (2) the chemical structure of interstellar dust; (3) interstellar abundances; and (4) the lifetime of a dust grain in the ISM. Presently this study is restricted to refractory interstellar material, i.e., the formation and destruction of ices are not included in the program. The program is embedded in an analytic solution for the bulk chemical evolution of a two-phase interstellar medium in which stars are born in molecular clouds, but new nucleosynthesis products and stellar return are entered into a complementary intercloud medium. The well-mixed matter of each interstellar phase is repeatedly cycled stochastically through the complementary phase and back. Refractory dust is created by thermal condensation as stellar matter flows away from sites of nucleosynthesis such as novae and supernovae and/or from the matter returned from evolved intermediate stars. The history of each particle is traced by standard Monte Carlo techniques as it is sputtered and fragmented by supernova shock waves in the intercloud medium. It also accretes an amorphous mantle of gaseous refractory atoms when its local medium joins with the molecular cloud medium. Finally it encounters the possibility of astration (destruction by star formation) within the molecular clouds.

  20. Respiratory allergy caused by house dust mites

    DEFF Research Database (Denmark)

    Calderón, Moisés A; Linneberg, Allan; Kleine-Tebbe, Jörg

    2015-01-01

    consequences in patients with respiratory allergic diseases. We investigate the epidemiology of HDM allergy to explore the interaction between mites and human subjects at the population, individual, and molecular levels. Core and recent publications were identified by using "house dust mite" as a key search...