WorldWideScience

Sample records for solution gas flaring

  1. Management of routine solution gas flaring in Alberta

    International Nuclear Information System (INIS)

    1998-01-01

    Alberta's Clean Air Strategic Alliance (CASA) shares decision-making responsibilities with the Government of Alberta for strategic aspects of air quality. In 1997, the Alliance established the Flaring Project Team to develop recommendations that address potential and observed impacts associated with flaring, with particular focus on 'upstream solution gas' flaring. The upstream industry explores for, acquires, develops, produces and markets crude oil and natural gas. Essentially, solution gas at upstream sites is 'co-produced' during crude oil production. The project team was established to collect and summarize information on flaring and its impacts and to develop recommendations for short-term actions to minimize the practice of routine flaring of solution gas. Another goal of the team is to develop a research strategy to better understand flaring emissions and their effects on human, animal and environmental health. The team is working on developing long-term strategies for actions to address the gas flaring issue. 5 refs., 1 tab., 7 figs

  2. Solution gas flaring and venting at Alberta primary crude bitumen operations

    Energy Technology Data Exchange (ETDEWEB)

    Ruff, C. [Alberta Energy and Utilities Board, Calgary, AB (Canada)

    2005-11-01

    The Alberta Energy and Utilities Board is mandated by the Government of Alberta to ensure fair, responsible development and delivery of energy resources and utilities services in Alberta while maintaining the best public interest. One of the agencies' priorities is the reduction of solution gas flaring and venting. The performance of solution gas flaring and venting in Alberta and best practices respecting solution gas conservation are discussed. Data was presented on solution gas production, solution gas conserved, and solution gas conservation efficiency. The paper described best practices solutions such as increased gas to oil (GOR) test frequency; predetermination of economic gas conservation; collaboration with county gas utilities; and utilization of portable and scalable gas compression. The paper also presents a discussion of the Clean Air Strategic Alliance (CASA), a non-profit multistakeholder that recommended enhancements to Guide 60. Requirements discussed include the requirement to conserve solution gas at certain sites exceeding established flare and vent volumes, gas conservation prebuild requirements, and enhanced economic evaluation process. 5 figs.

  3. Assessment of respiratory disorders in relation to solution gas flaring activities in Alberta

    International Nuclear Information System (INIS)

    1998-02-01

    A study was conducted by Alberta Health to address the issue of whether or not flaring of solution gas has a negative impact on human health. The Flaring Working Group of the Clean Air Strategic Alliance initiated this study which focused on the assessment of the relationship between human health disorders (such as asthma, bronchitis, pneumonia and upper respiratory infections) and solution gas flaring activities in rural, urban and aboriginal populations. The personal exposure to flaring emissions was estimated by physical proximity to the source of emissions. A small area was studied in which geographical variations in human health disorders were compared to geographical variations of socioeconomic and environmental factors. Data was gathered from 1989 to 1996 to evaluate long term average conditions and changes over the time period investigated. Notwithstanding physicians' claims for increased rates of respiratory infections and hospitalization attributed to solution gas flaring, the study found no evidence linking respiratory infections and solution gas flaring. This was the conclusion regardless of the measure of health outcomes, the rural-urban status, ethnicity, or age. Nevertheless, the study recommended identification of bio-markers of exposure and effect reflective of the compounds of interest, and the development of a responsive and comprehensive geographic information database that would allow data linkage at all geographic levels for different periods of time. refs., 10 tabs., 15 figs., 1 appendix

  4. The regulatory context of gas flaring in Alberta

    International Nuclear Information System (INIS)

    Gilmour, B.S.; Cook, C.

    1999-01-01

    The legislative and regulatory regime regarding gas flaring in Alberta was reviewed. The issue of gas flaring has received much attention from petroleum industry regulators in Alberta. Residents living in the vicinity of flares have identified them as sources of odour, smoke, noise and air quality-related health concerns. Sulfur dioxide and carbon dioxide emissions from the flare stacks may contribute to acid rain and the greenhouse effect. The Strosher Report, released by the Alberta Research Council in 1996, has also identified about 250 different compounds in flare emissions, including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and other products of incomplete combustion. The public opposition to solution gas flaring has caused regulators to consider new options designed to reduce the adverse economic and environmental impacts that may be associated with gas flaring. This paper discusses the roles of the Alberta Energy and Utilities Board (EUB) and Alberta Environmental Protection in administering legislation that impacts on gas flaring. In March 1999, the EUB released a guide containing the following five major points regarding gas flaring: (1) implementation of the Clean Air Strategic Alliance's (CASA's) recommendations to eventually eliminate flaring, by starting immediately to reduce flaring, and improve the efficiency of flares, (2) adoption of the CASA schedule of reduction targets for solution gas flaring, (3) conducting a review of the current approval process for small-scale electrical generation systems to encourage co-generation as a productive use of solution gas that is being flared, (4) creating better public notification requirements for new and existing facilities, and (5) discussing conflict resolution between operators and landowners. 26 refs

  5. Feasibility of flare gas reformation to practical energy in Farashband gas refinery: no gas flaring.

    Science.gov (United States)

    Rahimpour, Mohammad Reaza; Jokar, Seyyed Mohammad

    2012-03-30

    A suggested method for controlling the level of hazardous materials in the atmosphere is prevention of combustion in flare. In this work, three methods are proposed to recover flare gas instead of conventional gas-burning in flare at the Farashband gas refinery. These methods aim to minimize environmental and economical disadvantages of burning flare gas. The proposed methods are: (1) gas to liquid (GTL) production, (2) electricity generation with a gas turbine and, (3) compression and injection into the refinery pipelines. To find the most suitable method, the refinery units that send gas to the flare as well as the required equipment for the three aforementioned methods are simulated. These simulations determine the amount of flare gas, the number of GTL barrels, the power generated by the gas turbine and the required compression horsepower. The results of simulation show that 563 barrels/day of valuable GTL products is produced by the first method. The second method provides 25 MW electricity and the third method provides a compressed natural gas with 129 bar pressure for injection to the refinery pipelines. In addition, the economics of flare gas recovery methods are studied and compared. The results show that for the 4.176MMSCFD of gas flared from the Farashband gas refinery, the electricity production gives the highest rate of return (ROR), the lowest payback period, the highest annual profit and mild capital investment. Therefore, the electricity production is the superior method economically. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Fifty per cent reduction in solution gas flaring : a report to the Saddle Hills Awareness Committee

    International Nuclear Information System (INIS)

    1999-01-01

    Information by the Alberta Energy Company to the Saddle Hills Awareness Committee (SHAC) regarding company operations in the West Peace River Arch of the western Canadian Sedimentary Basin in northwest Alberta is presented, the purpose being to bring the Committee up-to-date, and respond to concerns about the health effects of sour gas emissions. The SHAC represents citizens who are concerned about issues relating to sour gas emissions. AEC West, a business unit of Alberta Energy Company, operates two sour gas processing plants, one sweet gas plant and three sour oil batteries in the Grande Prairie area. AEC's gas plants are connected by pipelines and process petroleum and natural gas products from approximately 200 oil and gas wells. The H 2 S content of the natural gas being processed by AEC's various plants ranges from trace amounts to 11 per cent. Activities at AEC's Hythe plant and at the Sexsmith plant, and the company's gas storage project are briefly reviewed. An analysis is included of the role that flaring plays in the petroleum and natural gas industry, emphasizing AEC West's efforts during 1997 to reduce solution gas flaring volumes from single well oil batteries by 50 per cent. Other AEC West environmental protection initiatives include the preliminary regional airshed study sponsored by the company which resulted in part from SHAC feedback and in part from the innovative approach of AEC employees. AEC West established the industry's first Ombudsman to provide a problem resolution focus on landowner complaints and introduced a policy of making available solution gas that would eventually be flared to industrial colleagues, free of charge

  7. Modelling emissions from natural gas flaring

    Directory of Open Access Journals (Sweden)

    G. Ezaina Umukoro

    2017-04-01

    Full Text Available The world today recognizes the significance of environmental sustainability to the development of nations. Hence, the role oil and gas industry plays in environmental degrading activities such as gas flaring is of global concern. This study presents material balance equations and predicts results for non-hydrocarbon emissions such as CO2, CO, NO, NO2, and SO2 etc. from flaring (combustion of 12 natural gas samples representing composition of natural gas of global origin. Gaseous emission estimates and pattern were modelled by coding material balance equations for six reaction types and combustion conditions with a computer program. On the average, anticipated gaseous emissions from flaring natural gas with an average annual global flaring rate 126 bcm per year (between 2000 and 2011 in million metric tonnes (mmt are 560 mmt, 48 mmt, 91 mmt, 93 mmt and 50 mmt for CO2, CO, NO, NO2 and SO2 respectively. This model predicted gaseous emissions based on the possible individual combustion types and conditions anticipated in gas flaring operation. It will assist in the effort by environmental agencies and all concerned to track and measure the extent of environmental pollution caused by gas flaring operations in the oil and gas industry.

  8. Flaring fix: better technologies green flaring

    International Nuclear Information System (INIS)

    Stastny, P.

    2004-01-01

    Recent advances in reducing solution gas flaring and venting are discussed, highlighting the 2002 report of the Clean Air Strategic Alliance (CASA) and its 39 recommendations targeting a 50 per cent reduction in flaring from a 1996 baseline. Much of the improvement to date (62 per cent at the end of 2002 on an annual basis) has come from collecting and sending gas down pipelines for processing, but improvements in technologies such as incineration, in combustion efficiency, and the use of micro-turbines, also helped to make a difference. Improvements in smokeless flares, through the addition of a special flare tip to flare stacks, has similarly contributed to higher combustion efficiency, and further improvements are expected from sonic flare technology currently under development. Expectations are also high for advances in incinerator technology, particularly enclosed burner systems, which almost completely burn flare gas while having no visible flame, smoke or odor

  9. Upstream petroleum industry flaring guide : review draft

    International Nuclear Information System (INIS)

    1999-03-01

    The Alberta requirements and expectations for upstream petroleum flaring are presented. Flaring is associated with a wide range of energy activities including oil and gas well drilling and well completion operations. The guide incorporates the recommendations made to the Alberta Energy and Utilities Board (EUB) in June 1998 by the multi-stakeholder Clean Air Strategic Alliance (CASA) on associated or solution gas flaring. Additional requirements which address flaring issues not covered in the CASA report are also included in this guide. The Guide requires a 15 per cent reduction in solution gas flare volume by the end of year 2000 from the 1996 baseline, and a 25 per cent reduction by the end of 2001. The Guide prescribes new flare performance requirements for all flares, within three years for existing solution gas flares, five years for flares at other existing permanent facilities. It sets personal consultation and public notification requirements for new and existing solution gas batteries, and new sulphur recovery requirements for facilities not covered by existing EUB regulations. The Guide also addresses the question of conflict resolution to deal with flaring concerns, the release of flaring and venting data, the proposed reduction of flare limits, progress towards minimizing requirements for electricity generators using otherwise flared gas, annual reporting to the EUB, and management framework review in 2001

  10. Exergy analysis of waste emissions from gas flaring

    Directory of Open Access Journals (Sweden)

    Olawale Saheed ISMAIL

    2016-07-01

    Full Text Available Gas flaring produces a stream of waste gases at high temperature and pressure which contains carbon monoxide, Hydrogen Sulphide etc. The resultant effect of which is detrimental to our planet and, consequently, to the life of both the living and the non-living things. It’s well known that gas flaring contributes in no small measure to the global warming. Exergy analysis is applied in this work to analyze waste emissions from gas flaring so as to have a model through which impact of gas flaring can be measured. The study considers both the thermo-mechanical exergy and the chemical exergy of these gases. Relevant data on gas flaring activities in the Niger-Delta region of Nigeria between the periods of fifteen (15 years was obtained from the Nigerian National Petroleum Corporation (NNPC. A computer program (Exergy Calculator was developed based on the equations generated in the Model. Exergy associated with gas flaring activities in Nigeria between the periods of 1998 through 2012 was calculated. The results show that 1 mscf (in thousand cubic feet of flared gases generate 0.000041 MWh of energy leading to a value of 440158.607 MWh of energy for the period under review.The analysis provides important conclusions and recommendations for improving oil platforms operationsin in order to safeguard the environment, health of the populace, and maximize recovered exergy from gas flaring.

  11. Progress report on recommendations of the Flaring Project Team

    International Nuclear Information System (INIS)

    Macken, C.

    1999-01-01

    Part of the mandate of the Clean Air Strategic Alliance (CASA) is to share decision-making responsibility for air quality management with the government of Alberta, through the ministries of Environmental Protection, Energy, and Health, and the Alberta Energy and Utilities Board (EUB). CASA's vision for air quality in Alberta is that 'the air will be odourless, tasteless, look clear, and have no measurable short- or long-term adverse effects on people, animals, or the environment'. In 1997, CASA approved the establishment of the Flaring Project Team in response to public concern about potential and observed impacts associated with flaring of solution gas. Members of that team established a framework for the management of solution gas flaring. Their long-term goal is to eliminate routine flaring of solution gas. The Project Team assessed existing information on solution gas flaring, including technologies, efficiencies, emissions and impacts. Alternative technologies were also reviewed along with biological and health effects of solution gas flaring. A list of data gaps and research needs was compiled in order to help with the development of the Team's recommendations. The Team's final report was delivered in June 1998. It was recommended that the following policy objective hierarchy be used to guide decisions related to routine solution gas flaring: (1) eliminate routine solution gas flaring, (2) reduce volumes of gas flared, and (3) improve the efficiency of flares. By way of progress the Project Team was able to report that in March, 1999, the EUB issued a draft interim directive to address upstream petroleum industry flaring. The draft Directive incorporates the recommendations from the CASA Flaring Project Team with respect to management of solution gas flaring. In December 1998, changes to the royalty structure to encourage the productive use of flare gas have been announced by the Alberta Department of Energy and Alberta Environmental protection, thus

  12. Technical and economic analysis use of flare gas into alternative energy as a breakthrough in achieving zero routine flaring

    Science.gov (United States)

    Petri, Y.; Juliza, H.; Humala, N.

    2018-03-01

    The activity of exploring natural oil and gas will produce gas flare 0.584 MMSCFD. A gas flare is the combustion of gas remaining to avoid poisonous gas like H2S and CO which is very dangerous for human and environmental health. The combustion can bring about environmental pollution and losses because it still contains valuable energy. It needs the policy to encourage the use of flare gas with Zero Routine Flaring and green productivity to reduce waste and pollution. The objective of the research was to determine the use of gas flare so that it will have economic value and can achieve Zero Routine Flaring. It was started by analysing based on volume or rate and composition gas flare was used to determine technical feasibility, and the estimation of the gas reserves as the determination of the economy of a gas well. The results showed that the use of flare gas as fuel for power generation feasible to be implemented technically and economically with Internal Rate of Return (IRR) 19.32% and the Payback Period (PP) 5 year. Thus, it can increase gas flare value economically and can achieve a breakthrough in Zero Routine Flaring.

  13. Field Measurements of Black Carbon Yields from Gas Flaring.

    Science.gov (United States)

    Conrad, Bradley M; Johnson, Matthew R

    2017-02-07

    Black carbon (BC) emissions from gas flaring in the oil and gas industry are postulated to have critical impacts on climate and public health, but actual emission rates remain poorly characterized. This paper presents in situ field measurements of BC emission rates and flare gas volume-specific BC yields for a diverse range of flares. Measurements were performed during a series of field campaigns in Mexico and Ecuador using the sky-LOSA optical measurement technique, in concert with comprehensive Monte Carlo-based uncertainty analyses. Parallel on-site measurements of flare gas flow rate and composition were successfully performed at a subset of locations enabling direct measurements of fuel-specific BC yields from flares under field conditions. Quantified BC emission rates from individual flares spanned more than 4 orders of magnitude (up to 53.7 g/s). In addition, emissions during one notable ∼24-h flaring event (during which the plume transmissivity dropped to zero) would have been even larger than this maximum rate, which was measured as this event was ending. This highlights the likely importance of superemitters to global emission inventories. Flare gas volume-specific BC yields were shown to be strongly correlated with flare gas heating value. A newly derived correlation fitting current field data and previous lab data suggests that, in the context of recent studies investigating transport of flare-generated BC in the Arctic and globally, impacts of flaring in the energy industry may in fact be underestimated.

  14. A Fifteen Year Record of Global Natural Gas Flaring Derived from Satellite Data

    International Nuclear Information System (INIS)

    Elvidge, Ch. D.; Erwin, E. H.; Ziskin, D.; Baugh, K. E.; Tuttle, B. T.; Ghosh, T.; Tuttle, B. T.; Ghosh, T.; Pack, D. W.; Zhizhin, M.

    2009-01-01

    We have produced annual estimates of national and global gas flaring and gas flaring efficiency from 1994 through 2008 using low light imaging data acquired by the Defense Meteorological Satellite Program (DMSP). Gas flaring is a widely used practice for the disposal of associated gas in oil production and processing facilities where there is insufficient infrastructure for utilization of the gas (primarily methane). Improved utilization of the gas is key to reducing global carbon emissions to the atmosphere. The DMSP estimates of flared gas volume are based on a calibration developed with a pooled set of reported national gas flaring volumes and data from individual flares. Flaring efficiency was calculated as the volume of flared gas per barrel of crude oil produced. Global gas flaring has remained largely stable over the past fifteen years, in the range of 140 to 170 billion cubic meters (BCM). Global flaring efficiency was in the seven to eight cubic meters per barrel from 1994 to 2005 and declined to 5.6 m 3 per barrel by 2008. The 2008 gas flaring estimate of 139 BCM represents 21% of the natural gas consumption of the USA with a potential retail market value of 68 billions USD. The 2008 flaring added more than 278 million metric tons of carbon dioxide equivalent (CO 2e ) into the atmosphere. The DMSP estimated gas flaring volumes indicate that global gas flaring has declined by 19% since 2005, led by gas flaring reductions in Russia and Nigeria, the two countries with the highest gas flaring levels. The flaring efficiency of both Russia and Nigeria improved from 2005 to 2008, suggesting that the reductions in gas flaring are likely the result of either improved utilization of the gas, reinjection, or direct venting of gas into the atmosphere, although the effect of uncertainties in the satellite data cannot be ruled out. It is anticipated that the capability to estimate gas flaring volumes based on satellite data will spur improved utilization of gas that

  15. Technical characterization and economic evaluation of recovery of flare gas in various gas-processing plants

    International Nuclear Information System (INIS)

    Zolfaghari, Mohabbat; Pirouzfar, Vahid; Sakhaeinia, Hossein

    2017-01-01

    Today in the worldwide quest for production and economic preference, only industries will survive that have proper solutions for waste disposal and environmental pollution. In industrial applications, a blow down network of gases is used in order to control system pressure and safety instruments. At the end of this network, the excess gases are burnt in the flare tower, which have severe consequences on the environment. Different methods have been proposed and several alternatives have been introduced for reduction and recovery of flaring gases. In this paper, three methods including gas to liquid (GTL), gas turbines generation (GTG) and gas to ethylene (GTE) are introduced and compared with the best method from economic point of view being identified. For this purpose, a natural gas sample is taken from Asalloyeh Refinery Plant and the process has been simulated using Aspen HYSYS. Meanwhile, estimation of the capital and operating costs and evaluation of the processes involved were made using Aspen Capital Cost Estimator. According to the results obtained, production of the electric power from flaring gases is one of the most economical methods. GTG method, with an annual profit of about 480e+006 $, has a greater ROR percent. - Highlights: • Three methods including GTL, GTG and GTE are developed for flare gas recovery. • The processes has been simulated using Aspen HYSYS. • Estimation of the capital and operating costs of the processes were made. • According to the results obtained, GTG is one of the most economical methods. • GTE method has the highest annual benefit, it has the lowest ROR percent.

  16. Gas Flaring: Carbon dioxide Contribution to Global Warming ...

    African Journals Online (AJOL)

    PROF HORSFALL

    emissions resulting from high consumption of fossil fuels. Flaring been a ... method of analysis showed that carbon dioxide from gas flaring constitute 1% of the total ... Although of these, methane is potentially the most .... in some gas plants.

  17. Modelling combustion reactions for gas flaring and its resulting emissions

    Directory of Open Access Journals (Sweden)

    O. Saheed Ismail

    2016-07-01

    Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

  18. Underground Storage Alternative To Nigeria's Gas Flaring

    International Nuclear Information System (INIS)

    Obi, A.I

    2004-01-01

    Energy demands are increasing as the world's population of energy users grows. At the same time many nations want to decommission nuclear plants in support of a cleaner environment. Clean burning natural gas is the fuel most likely to meet society's complex requirements. Demand for natural gas will rise more strongly than for any fossil fuel. The utilization of the huge gas resources form the petroleum deposit in the Niger Delta area is the major problem confronting the oil/gas industry in Nigeria and the disposal of associated gas has been a major challenge for the barrel of oil; hence with oil production of about 2.0 million barrels per day, some 2.0 billion standard cubic feet of AG is producing everyday. An alarming proportion of the gas is wasted by flaring, while very small proportion is used by oil-producing companies and other most alarming rate of flaring in the world compared with other oil/gas producing countries. This paper highlights the numerous benefits accruing from proper utilization of natural gas using SASOL of South Africa as an example and recommends underground storage of natural gas as an industry that will help check flaring, meet fluctuating demand and create wealth for the nation

  19. A global gas flaring black carbon emission rate dataset from 1994 to 2012

    Science.gov (United States)

    Huang, Kan; Fu, Joshua S.

    2016-11-01

    Global flaring of associated petroleum gas is a potential emission source of particulate matters (PM) and could be notable in some specific regions that are in urgent need of mitigation. PM emitted from gas flaring is mainly in the form of black carbon (BC), which is a strong short-lived climate forcer. However, BC from gas flaring has been neglected in most global/regional emission inventories and is rarely considered in climate modeling. Here we present a global gas flaring BC emission rate dataset for the period 1994-2012 in a machine-readable format. We develop a region-dependent gas flaring BC emission factor database based on the chemical compositions of associated petroleum gas at various oil fields. Gas flaring BC emission rates are estimated using this emission factor database and flaring volumes retrieved from satellite imagery. Evaluation using a chemical transport model suggests that consideration of gas flaring emissions can improve model performance. This dataset will benefit and inform a broad range of research topics, e.g., carbon budget, air quality/climate modeling, and environmental/human exposure.

  20. Health and exposure assessment of flare gas emissions

    International Nuclear Information System (INIS)

    Kindzierski, W.B.; Byrne-Lewis, C.; Probert, S.

    2000-01-01

    The incomplete combustion of flare gases produces pollutants such as volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) which are cause for concern for public health. Some of the concerns relate to potential long-term cumulative health effects from exposure to hazardous air pollutants including benzene, styrene, naphthalene, and benzopyrene. This study demonstrated that several factors should be taken into account when considering the importance of flaring and human exposure to flare gas emissions. Most flare stacks are located in rural areas, but most time-availability studies have been done on urban populations where the majority of people spend their time indoors. It was recommended that more time-activity studies are needed to emphasize the behaviour of rural populations which are most susceptible to exposure from pollutants from flaring. It was concluded that higher indoor air concentrations exist for many VOCs and PAHs compared to outdoors, but in these instances, indoor sources are the major contributors to indoor air concentrations. It was recommended that health assessments of hazardous air pollutants emitted from gas flaring has to take into account the indoor setting and other background exposures in order to provide useful information for decision makers. 49 refs., 8 tabs., 1 fig

  1. A flare for decommissioning : a push to close flare pits in B.C. earns Petro-Canada an industry award for environmental stewardship

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, J.

    2009-01-15

    Flaring is widely used to dispose of natural gas liberated during oil production and processing in remote areas where there is no pipeline on site to make use of the gas. Sources of flaring include well testing, solution gas from oil wells, underbalanced drilling, gas gathering systems and gas processing plants. Flaring is a source of pollution and a waste of energy. This article described Petro-Canada's efforts to eliminate flaring. In the late 1990s, the company began environmental assessments of its flare pits in British Columbia (BC). Since 2005, the producer has decommissioned 106 of its 108 pits in the province and ring-fenced the other 2. As the staff advanced the task of decommissioning, it often consolidated flaring hardware, installing a single, vertical flare stack to serve where 3 or 4 flare pits had previously served as many well sites. Before decommissioning began, Petro-Canada carried out its own environmental protocol and assessed its pits for the presence of contaminants and for their potential to leach into local waterways. Monitoring of groundwater through wells drilled on the company's BC flare pit sites will continue for some time, particularly on sites with bodies of water. BC's Oil and Gas Commission estimated that between 1996 and 2006, conservation of solution gas rose from 87 to 97 per cent among the province's producers. Petro-Canada was commended for being among the first to secure all flare pits under its control in BC. It was estimated that 49 per cent of all flare pits decommission in BC by 2007 were completed by Petro-Canada. 2 refs., 2 figs.

  2. CASA : oil and gas industry perspective : flaring : case study of success

    International Nuclear Information System (INIS)

    Pryce, D.

    2002-01-01

    A brief overview of the Canadian Association of Petroleum Producers (CAPP) and its mission is provided at the beginning of this presentation. The importance of flaring is explained, as it represents a safety precaution in the event of an emergency or process upset. It is also an important part of operations, and is valuable in well test evaluations for gathering information as part of the facility design process. Some of the major issues associated with flaring are reviewed, namely flare performance; concerns related to health risks, odour, visibility, greenhouse gases, resource conservation; the position of the Energy and Utilities Board (EUB), and the need of the industry for regulatory certainty. The Clean Air Strategic Alliance (CASA) was commissioned by the CAPP to examine the issue of flaring in November 1996 as part of the CASA flaring project team. The key recommendations of the CASA flaring team project were submitted in 1998 and included: focus on solution gas at oil batteries, the establishment of a new management framework. The author presents the Alberta provincial policy objective with regard to flaring. The best management practices decision tree is explained, along with management tools, which were incorporated in a new guide for flaring issued in July 1999 by the Alberta Energy and Utilities Board. The reduction targets are reviewed, and the author explains the rationale for the industry support of the recommendations. The progress to date is reviewed, and the next steps in the ongoing process are described, such as the formal progress review currently underway

  3. Oilfield Flare Gas Electricity Systems (OFFGASES Project)

    Energy Technology Data Exchange (ETDEWEB)

    Rachel Henderson; Robert Fickes

    2007-12-31

    The Oilfield Flare Gas Electricity Systems (OFFGASES) project was developed in response to a cooperative agreement offering by the U.S. Department of Energy (DOE) and the National Energy Technology Laboratory (NETL) under Preferred Upstream Management Projects (PUMP III). Project partners included the Interstate Oil and Gas Compact Commission (IOGCC) as lead agency working with the California Energy Commission (CEC) and the California Oil Producers Electric Cooperative (COPE). The project was designed to demonstrate that the entire range of oilfield 'stranded gases' (gas production that can not be delivered to a commercial market because it is poor quality, or the quantity is too small to be economically sold, or there are no pipeline facilities to transport it to market) can be cost-effectively harnessed to make electricity. The utilization of existing, proven distribution generation (DG) technologies to generate electricity was field-tested successfully at four marginal well sites, selected to cover a variety of potential scenarios: high Btu, medium Btu, ultra-low Btu gas, as well as a 'harsh', or high contaminant, gas. Two of the four sites for the OFFGASES project were idle wells that were shut in because of a lack of viable solutions for the stranded noncommercial gas that they produced. Converting stranded gas to useable electrical energy eliminates a waste stream that has potential negative environmental impacts to the oil production operation. The electricity produced will offset that which normally would be purchased from an electric utility, potentially lowering operating costs and extending the economic life of the oil wells. Of the piloted sites, the most promising technologies to handle the range were microturbines that have very low emissions. One recently developed product, the Flex-Microturbine, has the potential to handle the entire range of oilfield gases. It is deployed at an oilfield near Santa Barbara to run on waste gas

  4. Suitability of gas flare locations for Mini Gas-To-Liquid Technology ...

    African Journals Online (AJOL)

    Sultan

    three can deliver power to the grid via cables and 6 can support local energy and allied industry development. ... impacts of gas flaring e.g. Anikpo et al. (2013). While new ... of the popular ones include cogeneration, GTL and natural gas ...

  5. Gas flaring: Carbon dioxide contribution to global warming ...

    African Journals Online (AJOL)

    Journal Home > Vol 20, No 2 (2016) > ... The quantitative method of analysis showed that carbon dioxide from gas ... gas flaring cause environmental degradation, health risks and constitute financial loss to the local oil producing communities.

  6. A new MODIS based approach for gas flared volumes estimation: the case of the Val d'Agri Oil Center (Southern Italy)

    Science.gov (United States)

    Lacava, T.; Faruolo, M.; Coviello, I.; Filizzola, C.; Pergola, N.; Tramutoli, V.

    2014-12-01

    Gas flaring is one of the most controversial energetic and environmental issues the Earth is facing, moreover contributing to the global warming and climate change. According to the World Bank, each year about 150 Billion Cubic Meter of gas are being flared globally, that is equivalent to the annual gas use of Italy and France combined. Besides, about 400 million tons of CO2 (representing about 1.2% of global CO2 emissions) are added annually into the atmosphere. Efforts to evaluate the impact of flaring on the surrounding environment are hampered by lack of official information on flare locations and volumes. Suitable satellite based techniques could offers a potential solution to this problem through the detection and subsequent mapping of flare locations as well as gas emissions estimation. In this paper a new methodological approach, based on the Robust Satellite Techniques (RST), a multi-temporal scheme of satellite data analysis, was developed to analyze and characterize the flaring activity of the largest Italian gas and oil pre-treatment plant (ENI-COVA) located in Val d'Agri (Basilicata) For this site, located in an anthropized area characterized by a large environmental complexity, flaring emissions are mainly related to emergency conditions (i.e. waste flaring), being the industrial process regulated by strict regional laws. With reference to the peculiar characteristics of COVA flaring, the RST approach was implemented on 13 years of EOS-MODIS (Earth Observing System - Moderate Resolution Imaging Spectroradiometer) infrared data to detect COVA-related thermal anomalies and to develop a regression model for gas flared volume estimation. The methodological approach, the whole processing chain and the preliminarily achieved results will be shown and discussed in this paper. In addition, the possible implementation of the proposed approach on the data acquired by the SUOMI NPP - VIIRS (National Polar-orbiting Partnership - Visible Infrared Imaging

  7. Numerical simulation of a sour gas flare

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

    Due to the limited amount of information in the literature on sour gas flares and the cost of conducting wind tunnel and field experiments on sour flares, this presentation presented a modelling project that predicted the effect of operating conditions on flare performance and emissions. The objectives of the project were to adapt an existing numerical model suitable for flare simulation, incorporate sulfur chemistry, and run simulations for a range of conditions typical of sour flares in Alberta. The study involved the use of modelling expertise at the University of Utah, and employed large eddy simulation (LES) methods to model open flames. The existing model included the prediction of turbulent flow field; hydrocarbon reaction chemistry; soot formation; and radiation heat transfer. The presentation addressed the unique features of the model and discussed whether LES could predict the flow field. Other topics that were presented included the results from a University of Utah comparison; challenges of the LES model; an example of a run time issue; predicting the impact of operating conditions; and the results of simulations. Last, several next steps were identified and preliminary results were provided. Future work will focus on reducing computation time and increasing information reporting. figs.

  8. Natural gas domestic market development for total elimination of routine flares in Nigeria's upstream petroleum operations

    International Nuclear Information System (INIS)

    Sonibare, J.A.; Akeredolu, F.A.

    2006-01-01

    Several research findings confirmed that gaseous emissions and thermal radiation emanate from flaring activities during separation of oil from gas in the petroleum upstream operations. This, coupled with identified degradation potential of flares, makes flaring of about 71 million m 3 /day of associated gas a great concern. In this paper, several efforts hitherto made by government and organized private sectors at monetizing associated natural gas being flared on daily basis in Nigeria were reviewed. Domestic market development, if adopted, could eliminate routine gas flaring by 2008, meeting a goal set by Nigerian Government. Various scenarios considered showed that relatively minor amounts of natural gas could be consumed domestically for cooking; the balance would be absorbed by thermal electricity generation. It could lead to total consumption of between 92 and 140 million m 3 /day of natural gas in the country, representing a fraction of the domestic energy market

  9. Mitigation options : flare and vent mitigation undercuts CCS in trimming CO{sub 2} emissions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.

    2010-11-15

    This article reported on a study aimed at reducing flaring and venting associated with conventional heavy oil production. In particular, the study analyzed parameters such as the variability in flare volumes, flare gas composition and statistical distribution of volumes flared. The objective was to determine the most viable economic solution to reducing flare and vent volumes. In particular, the study focused on various scenarios to tie-in currently flared and vented solution gas. Solution gas volume variability was found to be wide ranging, with 90 percent of sites handling less than 32 percent of the volume and 10 percent of the sites handling more than two-thirds of the volume. Composition also varied, and was difficult to measure. One scenario assumed that wells were unconnected and had to be tied in with their own compressors and pipe, while another scenario considered the wells to be individual wells. A first comprehensive analysis of flare and vent mitigation opportunities in Alberta revealed that tying in solution gas at battery sites could create emissions reductions at much lower cost than the province's carbon capture and storage (CCS) plan. The study of mitigation options primarily targeted the conventional heavy oil belt of eastern Alberta near Lloydminster. The most optimistic scenario included a $15 per tonne carbon credit, that up to 55 megatonnes could be trimmed over 10 years at no cost to the industry.1 fig.

  10. Contributions of gas flaring to a global air pollution hotspot : spatial and temporal variations, impacts and alleviation

    OpenAIRE

    Anejionu, Obinna; Whyatt, Duncan; Blackburn, George Alan; Price, Catheryn

    2015-01-01

    Studies of environmental impacts of gas flaring in the Niger Delta are hindered by limited access to official flaring emissions records and a paucity of reliable ambient monitoring data. This study uses a combination of geospatial technologies and dispersion modelling techniques to evaluate air pollution impacts of gas flaring on human health and natural ecosystems in the region. Results indicate that gas flaring is a major contributor to air pollution across the region, with concentrations e...

  11. University of Alberta Flare Research Project : interim report November 1996-Jun 2000

    International Nuclear Information System (INIS)

    Kostiuk, L.; Johnson, M.

    2000-01-01

    The Flare Research Project at the University of Alberta is an ongoing multi year study into the emissions, combustion process and fluid mechanics related to flaring, which is commonly used in the energy and petrochemical industries to dispose of unwanted combustible gases by burning them in an open flame. This report focused on the emissions and efficiency of flares under operating conditions typical of solution gas flares. While most solution gas produced in Alberta is conserved, it is estimated that 6 per cent of these gases are flared with significant changes in the volumes flared from site to site. The median volume of flared or vented gas was approximately 60,300 m 3 /year and 95 per cent of battery sites flare and vent less than 1,000,000 m 3 /year. The goal of this project is to experimentally study the scaled-down generic pipe flares under well-controlled conditions to better understand the performance of flares. Research was conducted in a closed-loop wind tunnel to determine the effects of wind on flaring. Other objectives of the research are to develop methods for measuring the overall combustion efficiency of flares with either gaseous flare streams or those containing liquid droplets. Models for the scaling of plumes that disperse the products of combustion from flares as a function of wind speed, exit velocity and flare stack diameter were also examined. And finally, this research project measured the emissions of selected toxic compounds in both their vapor and soot phases. 38 refs., 10 tabs., 56 figs

  12. A satellite-based analysis of the Val d'Agri Oil Center (southern Italy) gas flaring emissions

    Science.gov (United States)

    Faruolo, M.; Coviello, I.; Filizzola, C.; Lacava, T.; Pergola, N.; Tramutoli, V.

    2014-10-01

    In this paper, the robust satellite techniques (RST), a multi-temporal scheme of satellite data analysis, was implemented to analyze the flaring activity of the Val d'Agri Oil Center (COVA), the largest Italian gas and oil pre-treatment plant, owned by Ente Nazionale Idrocarburi (ENI). For this site, located in an anthropized area characterized by a large environmental complexity, flaring emissions are mainly related to emergency conditions (i.e., waste flaring), as industrial processes are regulated by strict regional laws. While regarding the peculiar characteristics of COVA flaring, the main aim of this work was to assess the performances of RST in terms of sensitivity and reliability in providing independent estimations of gas flaring volumes in such conditions. In detail, RST was implemented for 13 years of Moderate Resolution Imaging Spectroradiometer (MODIS) medium and thermal infrared data in order to identify the highly radiant records associated with the COVA flare emergency discharges. Then, using data provided by ENI about gas flaring volumes in the period 2003-2009, a MODIS-based regression model was developed and tested. The results achieved indicate that the such a model is able to estimate, with a good level of accuracy (R2 of 0.83), emitted gas flaring volumes at COVA.

  13. Risk communications : an important part of the solution to the problem of gas flaring

    International Nuclear Information System (INIS)

    Kruk, G.E.

    1999-01-01

    The 'human' aspect of risk management as it relates to the problem of gas flaring was discussed in an effort to find an effective strategy for dealing with the problem. The 'human' aspect is important for both public consent and regulatory approval. The discipline of risk communications understands that the main issue is not the level of risk, but its acceptability to the public. The author believes that risk should be defined broadly so that it is not limited only to threats to public health and safety, but also to threats to the environment and quality of life. The five main strategic aspects of risk that influence the public's judgement of the level and acceptability of a risk are when: (1) the risk is created by organizations the public feels they cannot trust, (2) the risk is regarded as having been involuntarily imposed on them, (3) the public feels it has no personal control over project decisions, (4) the risk is viewed as unfair, and (5) the risk is managed by people who appear uncaring. A list of other influential factors was also provided. The ultimate objective of any risk communication strategy would be to enhance the affected public's ability to make an informed decision about the acceptability of the risk to which they are exposed. When dealing with the gas flaring problem, it is important to develop greater consensus of 'how safe is safe enough?' It was emphasized that trust is the most important factor in reducing public anxieties about risk and in strengthening relationships. The development of a strategy that has public support requires continuous stakeholder involvement

  14. Dealing with the gas flaring problem in the petroleum industry : proceedings of an Insight conference

    International Nuclear Information System (INIS)

    1999-01-01

    The 12 presentations at this conference focused on the environmental issues related to the flaring of waste gas in the petroleum industry, including the combustion efficiency of the process. Health issues associated with waste gas flaring were also discussed. Studies have identified about 250 different compounds in flare emissions, including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and other products of incomplete combustion. In recent years, public opposition to the oil companies in Alberta has become increasingly aggressive, with violence, bombings and other vandalism. Much of this hostile reaction was the result of the perceived harmful effects of flaring. The level of hostility generated by this phenomenon has caused regulators to consider new options designed to reduce the adverse economic and environmental impacts that may be associated with gas flaring. The papers presented at this Insight Conference review the background of the controversy, report on progress developing alternative combustion and incineration technologies for open flare systems, examine the economic and health issues involved, and outline current and proposed regulations. refs., tabs., figs

  15. Environmental pollution due to gas flaring at Oyigbo area of Rivers State

    International Nuclear Information System (INIS)

    Avwiri, G. O.; Ebeniro, J. O.

    1996-01-01

    Environmental degradation due to oil activities in the oil rich Niger Delta of Nigeria is daily approaching a non-tolerance level. Pollutants come from various aspects of operation ranging from seismic operations through drilling to the refinery stage. Gas flared daily by Oil Companies constitute a major health hazard in this country. Environmental pollution due to gas flaring at Oyigbo area of Rivers State is hereby reported. Surface temperature-distance variations were investigated for both dry (March) and rainy (June) seasons. Physical and chemical properties of the rainwater from the areas were also measured and analysed. The results show a surface temperature elevation of about 4.1 Celsius above the mean normal diurnal temperature within a 3.00 km. radius. An average pH 4.25 was recorded thus showing the acidic nature of the environmental rainwater from the area. All other measured parameters showed serious deviations from standards. This temperature elevation and increased acidity of the rainwater have enormous influence on socio-economic lives and the activities of the populace especially on their source of income which is mainly small scale farming. It is therefore necessary that Government agencies empowered to monitor environment especially FEPA should implement all the existing legislation on gas flaring and be more involved in the design and location of gas flaring stacks. These stacks should be located at least 2 km. from towns and villages

  16. A satellite-based analysis of the Val d'Agri (South of Italy) Oil Center gas flaring emissions

    Science.gov (United States)

    Faruolo, M.; Coviello, I.; Filizzola, C.; Lacava, T.; Pergola, N.; Tramutoli, V.

    2014-06-01

    In this paper the Robust Satellite Techniques (RST), a multi-temporal scheme of satellite data analysis, was implemented to analyze the flaring activity of the largest Italian gas and oil pre-treatment plant (i.e. the Ente Nazionale Idrocarburi - ENI - Val d'Agri Oil Center - COVA). For this site, located in an anthropized area characterized by a~large environmental complexity, flaring emissions are mainly related to emergency conditions (i.e. waste flaring), being the industrial process regulated by strict regional laws. With reference to the peculiar characteristics of COVA flaring, the main aim of this work was to assess the performances of RST in terms of sensitivity and reliability in providing independent estimations of gas flaring volumes in such conditions. In detail, RST was implemented on thirteen years of Moderate Resolution Imaging Spectroradiometer (MODIS) medium and thermal infrared data in order to identify the highly radiant records associated to the COVA flare emergency discharges. Then, exploiting data provided by ENI about gas flaring volumes in the period 2003-2009, a MODIS-based regression model was developed and tested. Achieved results indicate that such a model is able to estimate, with a good level of accuracy (R2 of 0.83), emitted gas flaring volumes at COVA.

  17. Gas Flaring, Environmental Pollution and Abatement Measures in ...

    African Journals Online (AJOL)

    The environmental impact of gas flaring on the oil bearing enclave of the Niger Delta, Nigeria, was examined with a view to evaluating the abatement measures put in place by the Federal government of Nigeria and the oil producing companies. Primary and secondary information and data were analyzed during the study.

  18. Quantifying Gas Flaring CH4 Consumption Using VIIRS

    Directory of Open Access Journals (Sweden)

    Xiaodong Zhang

    2015-07-01

    Full Text Available A method was developed to estimate the consumption of CH4 and the release of CO2 by gas flaring using VIIRS nighttime data. The results agreed with the field data collected at six stations in Bakken field, North Dakota, USA, within ±50%, as measured by mean relative errors and with a correlation coefficient of 0.75. This improved over the NOAA NightFire estimates, likely due to: (1 more stringent data selection using only the middle portion of cloud-free VIIRS nighttime imagery; (2 the use of a lower heating rate, which is more suitable for the field condition; and (3 more accurate efficiency factors in calculating completeness in combustion and conversion of total reaction energy into radiant energy that can be sensed by a satellite sensor. While using atmospherically-corrected data can further improve the estimate of CH4 consumption by ~10%, the major uncertainty remains as being the form factor of the flares, particularly the ratio of total surface area of a flare to the cross-section area that was seen by a satellite sensor.

  19. Evaluation of ground level concentration of pollutant due to gas flaring by computer simulation: A case study of Niger - Delta area of Nigeria

    Directory of Open Access Journals (Sweden)

    A. S. ABDULKAREEM

    2005-01-01

    Full Text Available The disposal of associated gases through flaring has been a major problem for the Nigerian oil and gas industries and most of theses gases are flared due to the lack of commercial out lets. The resultant effects of gas flaring are the damaging effect of the environment due to acid rain formation, green house effect, global warming and ozone depletion.This writes up is aimed at evaluating ground level concentration of CO2, SO2, NO2 and total hydrocarbon (THC, which are product of gas flared in oil producing areas. Volumes of gas flared at different flow station were collected as well as geometrical parameters. The results of simulation of model developed based on the principles of gaseous dispersion by Gaussian showed a good agreement with dispersion pattern.The results showed that the dispersion pattern of pollutants at ground level depends on the volume of gas flared, wind speed, velocity of discharge and nearness to the source of flaring. The results shows that continuous gas flaring irrespective of the quantity deposited in the immediate environment will in long run lead to change in the physicochemical properties of soil.

  20. Design alternatives, components key to optimum flares

    International Nuclear Information System (INIS)

    Cunha-Leite, O.

    1992-01-01

    A properly designed flare works as an emissions control system with greater than 98% combustion efficiency. The appropriate use of steam, natural gas, and air-assisted flare tips can result in smokeless combustion. Ground flare, otherwise the elevated flare is commonly chosen because it handles larger flow releases more economically. Flaring has become more complicated than just lighting up waste gas. Companies are increasingly concerned about efficiency. In addition, U.S. Occupational Safety and Health Administration (OSHA) and U.S. Environmental Protection Agency (EPA) have become more active, resulting in tighter regulations on both safety and emissions control. These regulations have resulted in higher levels of concern and involvement in safety and emissions matters, not to mention smoke, noise, glare, and odor. This first to two articles on flare design and components looks at elevated flares, flare tips, incinerator-type flares, flare pilots, and gas seals. Part 2 will examine knockout drums, liquid-seal drums, ignition systems, ground flares, vapor recovery systems, and flare noise

  1. Effect of Prolong Exposure to Gas Flaring on some Haematological ...

    African Journals Online (AJOL)

    MICHAEL

    Pollution of the air, land and water from gas flares or common oil blowouts and spill are regular occurrence in the region (Njeze, 1983). It has being suggested that though complete combustion process creates relatively innocuous gases such as carbon dioxide and water, such complete combustion is rarely achieved by ...

  2. Flaring research update

    International Nuclear Information System (INIS)

    Reynen, B.A.

    1999-01-01

    Several studies regarding waste gas flaring have been conducted in an effort to determine the potential health and environmental impacts associated with flaring. Energy source conservation and greenhouse gas emissions reduction are other reasons for studying the issue. A brief outline for each of the following research priorities was given: (1) operating practices, (2) flare performance, focusing on improved combustion efficiency, (3) speciation, addressing the potential effects of incomplete combustion, (4) alternative technologies such as membrane technology, cryogenics and power generation to reduce flare gas volume, (5) improved liquid separation, concentrating on the removal of entrained liquids to improve performance and reduce emissions and (6) fate and transport, including plume modeling, ambient air monitoring, tracking of known toxins, primarily to address concerns of environmental groups.The expectation is that this broad and comprehensive research effort will yield substantive and credible scientific data, lead to cooperation in the research community, reduce emissions, beneficially impact on regulations and standards and gain the support of environmental organizations

  3. Zero gas flaring in Niger Delta Area of Nigeria: a way to ...

    African Journals Online (AJOL)

    Open Access DOWNLOAD FULL TEXT Subscription or Fee Access ... interviews and direct and first-hand observation were used as sources of information. ... be compelled to stop flaring and put the gas into other domestic and industrial uses.

  4. A MODIS-based analysis of the Val d'Agri Oil Center (South of Italy) thermal emission: an independent gas flaring estimation strategy

    Science.gov (United States)

    Pergola, Nicola; Faruolo, Mariapia; Irina, Coviello; Carolina, Filizzola; Teodosio, Lacava; Valerio, Tramutoli

    2014-05-01

    Different kinds of atmospheric pollution affect human health and the environment at local and global scale. The petroleum industry represents one of the most important environmental pollution sources, accounting for about 18% of well-to-wheels greenhouse gas (GHG) emissions. The main pollution source is represented by the flaring of gas, one of the most challenging energy and environmental problems facing the world today. The World Bank has estimated that 150 billion cubic meters of natural gas are being flared annually, that is equivalent to 30% of the European Union's gas consumption. Since 2002, satellite-based methodologies have shown their capability in providing independent and reliable estimation of gas flaring emissions, at both national and global scale. In this paper, for the first time, the potential of satellite data in estimating gas flaring volumes emitted from a single on-shore crude oil pre-treatment plant, i.e. the Ente Nazionale Idrocarburi (ENI) Val d'Agri Oil Center (COVA), located in the Basilicata Region (South of Italy), was assessed. Specifically, thirteen years of night-time Moderate Resolution Imaging Spectroradiometer (MODIS) data acquired in the medium and thermal infrared (MIR and TIR, respectively) bands were processed. The Robust Satellite Techniques (RST) approach was implemented for identifying anomalous values of the signals under investigation (i.e. the MIR-TIR difference one), associated to the COVA flares emergency discharges. Then, the Fire Radiative Power (FRP), computed for the thermal anomalies previously identified, was correlated to the emitted gas flaring volumes, available for the COVA in the period 2003 - 2009, defining a satellite based regression model for estimating COVA gas flaring emitted volumes. The used strategy and the preliminary results of this analysis will be described in detail in this work.

  5. Monitoring air pollutants due to gas flaring using rain water | Rim ...

    African Journals Online (AJOL)

    The mean levels of conductivity, TDS, and SO42- were within statutory safe limits, while that of pH, CO32- and NO3- were above the safe limits specified by the Federal Ministry of Environment guidelines and standards for drinking water quality. Keywords: rainwater, gas flare, pollutants, monitoring, water quality

  6. Improved flare tip design

    Energy Technology Data Exchange (ETDEWEB)

    Gogolek, P. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre

    2004-07-01

    This paper discusses the testing procedures and development of an improved flare tip design. Design objectives included performance equal to or better than utility flares at low wind speed; conversion efficiency; fuel slip; smoking; significant improvement at high wind speed; and no increase in trace emissions. A description of the testing facility of the flare tip was provided, with reference to the fact that the facility allowed for realistic near full scale gas flares in a single-pass flare test facility. Other details of the facility included: an adjustable ceiling; high capacity variable speed fan; sampling ports along working section in stack; windows along working section; and air cooled walls, floor, and ceiling. The fuels used in the flare tip included natural gas, propane, gasoline and inert gases. Details of wind speed, appurtenances and turbulence generating grids were presented, with reference to continuous gas emission measurements. A list of design constraints was provided. Flare performance included wind speed, turbulence and fuel composition. A chart of conversion inefficiencies with a correlation of wind speed and turbulence, fuel flow and pipe size was also presented. Several new tip designs were fabricated for testing, with screening tests for comparison to basic pipe and ranking designs. Significant improvements were found in one of the new designs, including results with 30 per cent propane in fuel. Emissions reduction from 10 to 35 per cent were noted. It was concluded that future work should focus on evaluating improved tip for stability at low wind speeds. Fuel slips are the primary source of emissions, and it was recommended that further research is necessary to improve existing flare tips. tabs, figs.

  7. Monthly carbon emissions from natural-gas flaring and cement manufacture in the United States

    International Nuclear Information System (INIS)

    Blasing, T.J.; Hand, Kimberly

    2007-01-01

    Annual data on carbon emissions from fossil-fuel combustion and cement manufacture have been used in studies of the carbon cycle for the last few decades. However, annual data do not specify carbon emissions on the seasonal time-scales relevant to biospheric uptake and other processes affecting the carbon cycle. Estimates of monthly emissions from fossil-fuel consumption in the US have shown that an increasing percentage of the annual emissions are occurring during the growing season; however, carbon emitted from flaring natural gas at well sites was not accounted for in those emissions estimates, nor was carbon emitted during cement manufacture. Here we show that emissions from flaring, which amount around 0.1 % of all fossil-fuel carbon emissions in the US, have no clear and persistent annual pattern that can be detected in the data. In contrast, carbon emissions from cement manufacture, which add about 0.7% to carbon emissions from fossil fuels in the US, have a clear and persistent annual pattern including low values in late winter and early spring. In this paper, we provide a few remarks on carbon emissions from natural-gas flaring before presenting monthly emissions estimates. We then focus on the methodology for calculating carbon emissions from cement manufacture before presenting and discussing the monthly emissions estimates

  8. Gas Flaring in Nigeria. A Human Rights, Environmental and Economic Monstrosity

    International Nuclear Information System (INIS)

    Osuoka, Asume; Roderick, P.

    2005-06-01

    This Report tracks the flaring back to the closing days of colonial history, sketches the scale of the activity in what has become one of the world's biggest oil and gas producing countries, explains some of its implications for climate change and communities, shows how the practice constitutes a violation of human rights and is generally prohibited under the regulations, and concludes with recommendations for its elimination, and transparency

  9. Comparison of high-temperature flare models with observations and implications for the low-temperature flare

    International Nuclear Information System (INIS)

    Machado, M.E.; Emslie, A.G.

    1979-01-01

    We analyze EUV data from the Harvard College Observatory and Naval Research Laboratory instruments on board the Skylab Apollo Telescope Mount, together with SOLRAD 9 X-ray data, in order to empirically deduce the variation of emission measure with temperature in the atmosphere of a number of solar flares. From these data we construct a ''mean'' differential emission measure profile Q (T) for a flare, which we find to be characterized by a low-lying plateau at temperatures of a few hundred thousand K, representative of a thin transition zone at these temperatures.We then compare this empirical profile with that predicted by a number of theoretical models, each of which represents a solution of the energy equation for the flare under various simplifying assumptions. In this way we not only deduce estimates of various flare parameters, such as gas pressure, but also gain insight into the validity of the various modeling assumptions employed.We find that realistic flare models must include both conductive and radiative terms in the energy equation, and that hydrodynamic terms may be important at low temperatures. Considering only models which neglect this hydrodynamic term, we compute conductive fluxes at various levels in the high-temperature plasma and compare them to the observed radiated power throughout the atmosphere, with particular reference to the 1973 September 5 event, which is rich in observations throughout most of the electromagnetic spectrum. This comparison yields results which reinforce our belief in the dominance of the conduction and radiation terms in the flare energy balance.The implications of this result for flare models in general is discussed; in particular, it is shown that the inclusion of the conductive term into models which have hitherto neglected it can perhaps resolve some of the observational difficulties with such models

  10. Prediction and comparison of noise levels from ground and elevated flare systems

    International Nuclear Information System (INIS)

    Obasi, E.

    2009-01-01

    Flaring is a process to dispose of hydrocarbons during clean-up, emergency shut downs or dispose a small volume waste streams of mixed gasses that cannot easily or safely be separated. This presentation discussed flaring as a noise issue. It focused on flaring noise characterization; flare noise modeling; flare sound power levels; and flare sound pressure level comparison at a distance of 1.5 km. The presentation included a photograph of flaring at a gas plant in Nigeria. The presentation listed some of the potential health effects associated with long term exposure to excessive noise, such as hearing loss; headaches; stress; fatigue; sleep disturbance; and high blood pressure. Companies flare gas to dispose waste gases in a safe and reliable manner through combustion and to depressurize gas lines during maintenance and emergencies. This presentation also discussed ground and elevated flares; components of flare noise characterization; and key factors affecting flare noise. A model to predict flaring noise was also presented. It demonstrated that at the same gas mass flow rate, the noise level from elevated flare stacks are significantly higher than ground flares. tabs., figs.

  11. Prediction and comparison of noise levels from ground and elevated flare systems

    Energy Technology Data Exchange (ETDEWEB)

    Obasi, E. [Stantec Consulting Ltd., Surrey, BC (Canada)

    2009-07-01

    Flaring is a process to dispose of hydrocarbons during clean-up, emergency shut downs or dispose a small volume waste streams of mixed gasses that cannot easily or safely be separated. This presentation discussed flaring as a noise issue. It focused on flaring noise characterization; flare noise modeling; flare sound power levels; and flare sound pressure level comparison at a distance of 1.5 km. The presentation included a photograph of flaring at a gas plant in Nigeria. The presentation listed some of the potential health effects associated with long term exposure to excessive noise, such as hearing loss; headaches; stress; fatigue; sleep disturbance; and high blood pressure. Companies flare gas to dispose waste gases in a safe and reliable manner through combustion and to depressurize gas lines during maintenance and emergencies. This presentation also discussed ground and elevated flares; components of flare noise characterization; and key factors affecting flare noise. A model to predict flaring noise was also presented. It demonstrated that at the same gas mass flow rate, the noise level from elevated flare stacks are significantly higher than ground flares. tabs., figs.

  12. Anthropogenic activities impact on atmospheric environmental quality in a gas-flaring community: application of fuzzy logic modelling concept.

    Science.gov (United States)

    Akintola, Olayiwola Akin; Sangodoyin, Abimbola Yisau; Agunbiade, Foluso Oyedotun

    2018-05-24

    We present a modelling concept for evaluating the impacts of anthropogenic activities suspected to be from gas flaring on the quality of the atmosphere using domestic roof-harvested rainwater (DRHRW) as indicator. We analysed seven metals (Cu, Cd, Pb, Zn, Fe, Ca, and Mg) and six water quality parameters (acidity, PO 4 3- , SO 4 2- , NO 3 - , Cl - , and pH). These were used as input parameters in 12 sampling points from gas-flaring environments (Port Harcourt, Nigeria) using Ibadan as reference. We formulated the results of these input parameters into membership function fuzzy matrices based on four degrees of impact: extremely high, high, medium, and low, using regulatory limits as criteria. We generated indices that classified the degree of anthropogenic activity impact on the sites from the product membership function matrices and weight matrices, with investigated (gas-flaring) environment as between medium and high impact compared to those from reference (residential) environment that was classified as between low and medium impact. Major contaminants of concern found in the harvested rainwater were Pb and Cd. There is also the urgent need to stop gas-flaring activities in Port Harcourt area in particular and Niger Delta region of Nigeria in general, so as to minimise the untold health hazard that people living in the area are currently faced with. The fuzzy methodology presented has also indicated that the water cannot safely support potable uses and should not be consumed without purification due to the impact of anthropogenic activities in the area but may be useful for other domestic purposes.

  13. Effect of flow parameters on flare stack generator noise

    International Nuclear Information System (INIS)

    Dinn, T.S.

    1998-01-01

    The SoundPLAN Computer Noise Model was used to determine the general effect of flare noise in a community adjacent to a petrochemical plant. Tests were conducted to determine the effect of process flow conditions and the pulsating flame on the flare stack generator noise from both a refinery flare and process flare. Flaring under normal plant operations, the flaring of fuel gas and the flaring of hydrogen were the three conditions that were tested. It was shown that the steam flow rate was the determining factor in the flare stack generated noise. Variations in the water seal level in the flare line surge tank increased or decreased the gas flowrate, which resulted in a pulsating flame. The period and amplitude of the pulsating noise from the flare stacks was determined by measuring several parameters. Flare stack noise oscillations were found to be greater for the process flare than for the refinery flare stack. It was suggested that minimizing the amount of steam fed to the flare and improving the burner design would minimize noise. 2 tabs., 6 figs

  14. Effect of Gas Flaring on the Environment: A Case Study of a Part of Niger Delta, Nigeria

    Science.gov (United States)

    Akeem, N. A.; Anifowose, A. Y. B.

    2016-12-01

    Gas flaring is a common practice in the Niger Delta region of Nigeria. It releases greenhouse gases into the atmosphere and causes reduction in the biodiversity and health status of inhabitants of the environment. This study examines the use of Remote Sensing and GIS in assessing the impact of gas flaring on water quality, land surface temperature (LST), and vegetation cover within the study area. Landsat imageries (1987, 2002 and 2015) covering the study area were utilized in carrying out time series analysis to compare pollution of surface water, land surface temperature and Normalized Difference Vegetation Index (NDVI) changes. The water quality parameters investigated are pH, Nitrate, Lead, Iron, Sulphate and Total Dissolve Solids. The pH and nitrate values obtained were not within the standard limits set by W.H.O.; they range between 4.12-6.04 and 80.50-88.30mg/l respectively. Values range between 0.0-0.04 mg/l for Pb, 0.01-1.20 mg/l for Fe, 39.98-245.60 mg/l for SO4, and 0.0-7.0 mg/l for TDS. The area covered with vegetation reduced from 63.0% to 54.2% and to 46.4%, with the area occupied by unhealthy vegetation increasing from 49.61% to 53.87% and a further decrease to 48.1%. It was also observed that the volume of gas flared had a direct impact on the variation of the land surface temperature with the mean LST of 1987 as 28.1oC, increasing to 31.3oC in 2002 and decreasing to 25.5oC in 2015. The results therefore revealed gas flaring as a significant factor responsible for unfavorable water quality, high temperature variation and the rapid decline in the health of natural vegetation of the study area.

  15. Central Africa Energy: Utilizing NASA Earth Observations to Explore Flared Gas as an Energy Source Alternative to Biomass in Central Africa

    Science.gov (United States)

    Jones, Amber; White, Charles; Castillo, Christopher; Hitimana, Emmanuel; Nguyen, Kenny; Mishra, Shikher; Clark, Walt

    2014-01-01

    Much of Central Africa's economy is centered on oil production. Oil deposits lie below vast amounts of compressed natural gas. The latter is often flared off during oil extraction due to a lack of the infrastructure needed to utilize it for productive energy generation. Though gas flaring is discouraged by many due to its contributions to greenhouse emissions, it represents a waste process and is rarely tracked or recorded in this region. In contrast to this energy waste, roughly 80% of Africa's population lacks access to electricity and in turn uses biomass such as wood for heat and light. In addition to the dangers incurred from collecting and using biomass, the practice commonly leads to ecological change through the acquisition of wood from forests surrounding urban areas. The objective of this project was to gain insight on domestic energy usage in Central Africa, specifically Angola, Gabon, and the Republic of Congo. This was done through an analysis of deforestation, an estimation of gas flared, and a suitability study for the infrastructure needed to realize the natural gas resources. The energy from potential natural gas production was compared to the energy equivalent of the biomass being harvested. A site suitability study for natural gas pipeline routes from flare sites to populous locations was conducted to assess the feasibility of utilizing natural gas for domestic energy needs. Analyses and results were shared with project partners, as well as this project's open source approach to assessing the energy sector. Ultimately, Africa's growth demands energy for its people, and natural gas is already being produced by the flourishing petroleum industry in numerous African countries. By utilizing this gas, Africa could reduce flaring, recuperate the financial and environmental loss that flaring accounts for, and unlock a plentiful domestic energy source for its people. II. Introduction Background Africa is home to numerous burgeoning economies; a

  16. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2013-09-01

    Full Text Available Arctic haze is a seasonal phenomenon with high concentrations of accumulation-mode aerosols occurring in the Arctic in winter and early spring. Chemistry transport models and climate chemistry models struggle to reproduce this phenomenon, and this has recently prompted changes in aerosol removal schemes to remedy the modeling problems. In this paper, we show that shortcomings in current emission data sets are at least as important. We perform a 3 yr model simulation of black carbon (BC with the Lagrangian particle dispersion model FLEXPART. The model is driven with a new emission data set ("ECLIPSE emissions" which includes emissions from gas flaring. While gas flaring is estimated to contribute less than 3% of global BC emissions in this data set, flaring dominates the estimated BC emissions in the Arctic (north of 66° N. Putting these emissions into our model, we find that flaring contributes 42% to the annual mean BC surface concentrations in the Arctic. In March, flaring even accounts for 52% of all Arctic BC near the surface. Most of the flaring BC remains close to the surface in the Arctic, so that the flaring contribution to BC in the middle and upper troposphere is small. Another important factor determining simulated BC concentrations is the seasonal variation of BC emissions from residential combustion (often also called domestic combustion, which is used synonymously in this paper. We have calculated daily residential combustion emissions using the heating degree day (HDD concept based on ambient air temperature and compare results from model simulations using emissions with daily, monthly and annual time resolution. In January, the Arctic-mean surface concentrations of BC due to residential combustion emissions are 150% higher when using daily emissions than when using annually constant emissions. While there are concentration reductions in summer, they are smaller than the winter increases, leading to a systematic increase of

  17. Economical Utilization of Associated Gas in Nigeria

    Directory of Open Access Journals (Sweden)

    Lukman Obayopo Alimi

    2014-07-01

    Full Text Available Oil production is often accompanied by associated natural gas as valuable by-product of oil processing. Large amount of this vital energy component is flared during these processes, mostly in developing countries. For a longer period of time more gas is flares in Nigeria than anywhere else in Africa and second to Russian in the world, with daily estimates of roughly 2.5 billion cubic feet. This is equivalent to around 40% of all Africa´s natural gas consumption, and annual financial loss to Nigeria is about 1.8 billion Euros. Gas flaring contributes to major environmental pollution problems, which affects oil producing areas of the Niger Delta in Nigeria. This research attempts to look into the environmental issues in the region and proposes possible solutions, with recommendations that will contribute to improve associated gas utilization. This study describes gas to liquid (GTL conversion technology as a sustainable option to utilize associated gas in Nigeria, and also evaluates the economic attractiveness of the process. This conversion technology could contribute to total elimination of gas flaring and reduces the overdependence on importation of refined products (petrol, diesel and kerosene from foreign countries into Nigeria.

  18. The thermal phase of solar flares

    International Nuclear Information System (INIS)

    Hirayama, Tadashi

    1979-01-01

    This paper is described on the observation of the flares, and then the numerical simulation on the structural change in the corona and the chromosphere during the flare is briefly discussed. Most of the flares occur on the active region where the density and the electron temperature are higher than those in the quiet region. The temperature and density increase after the flare started. The temperature of the pre-flare chromosphere is about 6000 K, and it rises during the flare. The temperature of the transition region is about 10 5 K, and the gas pressure increases more than one order of magnitude during the flare. Sometimes, the flaring in the photosphere is observed. Large amount of mass ejected at the time of the flare is observed. Most probable energy source of the flare is the magnetic energy contained in the form of electric current. Liberation of this energy into the corona is discussed in this paper. It is assumed that a column of unit area is standing vertically in the corona, the top being closed. A hydrostatic model of the corona-chromosphere is constructed, in which the heat source is assumed to be in the corona. As the results of calculation, it can be said that the temperature of the flaring corona does not depend upon the liberated energy, the density in the corona increases proportionally to the energy, and particles are supplied from the chromosphere with the upward velocity of about 100 km/s. The gas pressure of the transition region can become up to three orders of magnitude larger. All these are consistent with the observation. Extension of this calculation is also performed. (Kato, T.)

  19. Reducing gas flaring in Russia: Gloomy outlook in times of economic insecurity

    International Nuclear Information System (INIS)

    Loe, Julia S.P.; Ladehaug, Olga

    2012-01-01

    Reducing Russia,s high levels of Associated Petroleum Gas (APG) flaring has been high on the Russian political agenda since 2007. In 2009 a decree requiring APG utilization of minimum 95 percent was adopted, valid from 1 January 2012. The oil industry has implemented various measures to reduce flaring, but not to a sufficiently large extent to make the 2012 deadline. This paper concludes that the utilization goal could be reached within 3–5 years if there is political will and the oil industry is given appropriate enabling measures. However, in a time of economic insecurity, domestically as well as in Russia’s primary export market in Europe, maintaining the status quo to ensure political stability is likely to be prioritized by the authorities at the expense of investments and structural reform which may be a premise for reaching the APG utilization goal. - Highlights: ► Russia's APG utilization goal will most likely not be reached within 3-5 years. ► The main reason for not reaching the 95 % target is lack of political will. ► Petroleum producers lack enabling measures for APG utilization. ► Reaching the target will most likely require structural gas sector reform. ► Reform is unlikely due to prioritization of political stability.

  20. Solar flares

    International Nuclear Information System (INIS)

    Brown, J.C.; Smith, D.F.

    1980-01-01

    The current observational and theoretical status of solar flares as a typical astrophysical problem is reviewed with especial reference to the intense and complex energy release in large flares. Observations and their diagnostic applications are discussed in three broad areas: thermal radiation at temperatures T 5 K; thermal radiation at T > approximately 10 5 K; and non-thermal radiation and particles. Particular emphasis is given to the most recent observational discoveries such as flare γ-rays, interplanetary Langmuir waves, and the ubiquitous association of soft x-ray loops with flares, and also the progress in particle diagnostics of hard x-ray and radio bursts. The theoretical problems of primary energy release are considered in terms of both possible magnetic configuration and in plasma instabilities and the question of achieving the necessary flash power discussed. The credibility of models for the secondary redistribution through the atmosphere of the primary magnetic energy released in terms of conduction, convection, radiation and particle transport is examined. Progress made in the flare problem in the past decade is assessed and some possible reasons why no convincing solution has yet been found are considered. 296 references. (U.K.)

  1. Clearing the air: Alberta a model of success in decreasing venting, flaring

    International Nuclear Information System (INIS)

    Harrison, L.

    2004-01-01

    An historical review of flaring and venting in the Alberta oilfields is presented. The story begins with gas production in the Turner Valley, Alberta in 1931, Western Canada's first, largest and most productive source of oil and naphtha until the discovery of Leduc in 1947. Gas production at Turner Valley reached 500 mmcf per day, of which about 486 mmcf was flared. Through the efforts of the Alberta Energy and Utilities Board (EUB) and its predecessors venting and flaring was drastically cut, to the point where in 2003 the World Bank Group, an agency of the United Nations, approached the EUB to present the Alberta flaring and venting reduction model to developing countries. Accordingly, a Flaring Workshop was held at Calgary in October 2003, attended by delegates from Algeria, Angola, Cameroon, Indonesia and Nigeria. The article also details the EUB's requirements for upstream flaring in Alberta, as laid down in 'Guide 60'. The draft Guide was released in January 2003, the final draft is targeted for February 2004. In brief, the Guide requires operators, by means of a 'decision tree analysis' method which is described in the Guide, to evaluate whether it is possible to reduce or eliminate flaring and venting; it also requires operators to evaluate economic feasibility, and to determine the feasibility of conserving as much gas as possible. New developments in the field of sensors, controls and optical flow meters are also reviewed. An appended statistical summary of gas flaring trends in selected countries, compiled by the World Bank in 2000 shows Nigeria, Iran, Russia, Algeria and Mexico as the countries with the highest volumes of flaring. To give an indication of the volume of gas wasted through flaring, it is reliably estimated that the amount of gas flared in 2000 by African countries alone, could have fuelled power plants to generate sufficient electric power to meet fully half of the continent's needs for electric power. 1 tab., 2 figs

  2. University of Alberta Flare Research Project : characterization of gases and liquids flared at battery sites in the Western Canadian Sedimentary Basin

    International Nuclear Information System (INIS)

    Kostiuk, L.W.; Thomas, G. P.

    2004-01-01

    Flaring is commonly used in the energy and petrochemical industries to dispose of unwanted combustible gases by burning them in an open flame. The Flare Research Project at the University of Alberta is an ongoing multiyear study into the emissions, combustion process and fluid mechanics related to flaring. This report presents the results of one phase of the study which characterizes the nature and relative quantities of gases and liquids being flared at seven battery sites in the Western Canadian Sedimentary Basin. A sampling system was specially developed to collect and analyze both the gas and liquid component of the flare stream. The analysis was performed by an independent chemical analysis company. Results indicate that no liquids were collected or observed at any of the sites, dispelling the assumption that liquids are commonly found in flare streams. Analysis of the gas phase showed a wide variation in the volume fraction of fuel and inert components. No correlation was made to link the appearance of smoke at a flare site to the composition of the flare gases. The preliminary tests provide the foundation for recommendations for future work regarding sampling programs and issues of combustion efficiency. 1 tab., 4 figs., 1 appendix

  3. Investigations of Flare Gas Emissions in Taq Taq Oil Field on the Surrounding Land

    Directory of Open Access Journals (Sweden)

    Jafar A. Ali

    2014-11-01

    Full Text Available Environmental pollution caused by oil takes many different forms; one of the most damaging sources is simply the combustion of oil products, such as a well flare burn-off. This paper presents the results of a survey of the agriculture lands around the Taq Taq Oil Production Company. The aim of the survey was to determine the potential contamination caused by the gas emissions from the well flares. Taq Taq field is located in the Kurdistan Region of Iraq, 60 km north of the giant Kirkuk oil field, 85 km south-east of Erbil and 120 km north-west of Suleimani. Samples of soil were collected from several locations around the site and analyzed to determine the content of Polycyclic Aromatic Hydrocarbons PAH present. A gas chromatography linked to a mass spectrometry (GCMS machine was used for these measurements. The PAH contamination at each location of soil was determined and the 16-PAHs, as listed in the US Environmental Protection Agency (EPA documentation were investigated. The average content of total PAH in all samples of the agricultural soil was 0.654 mg·kg-1 with the concentrations ranging from 0.310 to 0.869 mg·kg-1. It was found that the PAH concentrations decreased with increasing distance from the TTOPCO oil field, indicating that pollution was evident, the area close to the field being more affected by the gas pollution.

  4. University of Alberta Flare Research Project : characterization of gases and liquids flared at battery sites in the Western Canadian Sedimentary Basin

    International Nuclear Information System (INIS)

    2004-01-01

    The Flare Research Project at the University of Alberta is an ongoing multi year study into the emissions, combustion process and fluid mechanics related to flaring, which is commonly used in the energy and petrochemical industries to dispose of unwanted combustible gases by burning them in an open flame. This report presents the results of one phase of the study which characterizes the nature and relative quantities of gases and liquids being flared at seven battery sites in the Western Canadian Sedimentary Basin. A sampling system was specially developed to collect and analyze both the gas and liquid component of the flare stream. The analysis was performed by an independent chemical analysis company. Results indicate that no liquids were collected or observed at any of the sites, dispelling the assumption that liquids are commonly found in flare streams. Analysis of the gas phase showed a wide variation in the volume fraction of fuel and inert components. No correlation was made to link the appearance of smoke at a flare site to the composition of the flare gases. The preliminary tests provide the foundation for recommendations for future work regarding sampling programs and issues of combustion efficiency tab., 4 figs., 1 appendix

  5. Sources of uncertainty in characterizing health risks from flare emissions

    International Nuclear Information System (INIS)

    Hrudey, S.E.

    2000-01-01

    The assessment of health risks associated with gas flaring was the focus of this paper. Health risk assessments for environmental decision-making includes the evaluation of scientific data to identify hazards and to determine dose-response assessments, exposure assessments and risk characterization. Gas flaring has been the cause for public health concerns in recent years, most notably since 1996 after a published report by the Alberta Research Council. Some of the major sources of uncertainty associated with identifying hazardous contaminants in flare emissions were discussed. Methods to predict human exposures to emitted contaminants were examined along with risk characterization of predicted exposures to several identified contaminants. One of the problems is that elemental uncertainties exist regarding flare emissions which places limitations of the degree of reassurance that risk assessment can provide, but risk assessment can nevertheless offer some guidance to those responsible for flare emissions

  6. Solar flare irradiation records in Antarctic meteorites

    International Nuclear Information System (INIS)

    Goswami, J.N.

    1981-01-01

    Observations of solar flare heavy nuclei tracks in eight Antartic meteorite samples are reported. Two of these were interior specimens from an L-3 chondrite which contained track-rich grains (olivine) indicating their exposure to solar flare irradiation before compaction of the meteorite. Preliminary noble gas data also indicate the presence of solar-type gases. (U.K.)

  7. On the Solution of the Continuity Equation for Precipitating Electrons in Solar Flares

    Science.gov (United States)

    Emslie, A. Gordon; Holman, Gordon D.; Litvinenko, Yuri E.

    2014-01-01

    Electrons accelerated in solar flares are injected into the surrounding plasma, where they are subjected to the influence of collisional (Coulomb) energy losses. Their evolution is modeled by a partial differential equation describing continuity of electron number. In a recent paper, Dobranskis & Zharkova claim to have found an "updated exact analytical solution" to this continuity equation. Their solution contains an additional term that drives an exponential decrease in electron density with depth, leading them to assert that the well-known solution derived by Brown, Syrovatskii & Shmeleva, and many others is invalid. We show that the solution of Dobranskis & Zharkova results from a fundamental error in the application of the method of characteristics and is hence incorrect. Further, their comparison of the "new" analytical solution with numerical solutions of the Fokker-Planck equation fails to lend support to their result.We conclude that Dobranskis & Zharkova's solution of the universally accepted and well-established continuity equation is incorrect, and that their criticism of the correct solution is unfounded. We also demonstrate the formal equivalence of the approaches of Syrovatskii & Shmeleva and Brown, with particular reference to the evolution of the electron flux and number density (both differential in energy) in a collisional thick target. We strongly urge use of these long-established, correct solutions in future works.

  8. An operational integrated short-term warning solution for solar radiation storms: introducing the Forecasting Solar Particle Events and Flares (FORSPEF) system

    Science.gov (United States)

    Anastasiadis, Anastasios; Sandberg, Ingmar; Papaioannou, Athanasios; Georgoulis, Manolis; Tziotziou, Kostas; Jiggens, Piers; Hilgers, Alain

    2015-04-01

    We present a novel integrated prediction system, of both solar flares and solar energetic particle (SEP) events, which is in place to provide short-term warnings for hazardous solar radiation storms. FORSPEF system provides forecasting of solar eruptive events, such as solar flares with a projection to coronal mass ejections (CMEs) (occurrence and velocity) and the likelihood of occurrence of a SEP event. It also provides nowcasting of SEP events based on actual solar flare and CME near real-time alerts, as well as SEP characteristics (peak flux, fluence, rise time, duration) per parent solar event. The prediction of solar flares relies on a morphological method which is based on the sophisticated derivation of the effective connected magnetic field strength (Beff) of potentially flaring active-region (AR) magnetic configurations and it utilizes analysis of a large number of AR magnetograms. For the prediction of SEP events a new reductive statistical method has been implemented based on a newly constructed database of solar flares, CMEs and SEP events that covers a large time span from 1984-2013. The method is based on flare location (longitude), flare size (maximum soft X-ray intensity), and the occurrence (or not) of a CME. Warnings are issued for all > C1.0 soft X-ray flares. The warning time in the forecasting scheme extends to 24 hours with a refresh rate of 3 hours while the respective warning time for the nowcasting scheme depends on the availability of the near real-time data and falls between 15-20 minutes. We discuss the modules of the FORSPEF system, their interconnection and the operational set up. The dual approach in the development of FORPSEF (i.e. forecasting and nowcasting scheme) permits the refinement of predictions upon the availability of new data that characterize changes on the Sun and the interplanetary space, while the combined usage of solar flare and SEP forecasting methods upgrades FORSPEF to an integrated forecasting solution. This

  9. Flare Energy Release: Internal Conflict, Contradiction with High Resolution Observations, Possible Solutions

    Science.gov (United States)

    Pustilnik, L.

    2017-06-01

    All accepted paradigm of solar and stellar flares energy release based on 2 whales: 1. Source of energy is free energy of non-potential force free magnetic field in atmosphere above active region; 2. Process of ultrafast dissipation of magnetic fields is Reconnection in Thin Turbulent Current Sheet (RTTCS). Progress in observational techniques in last years provided ultra-high spatial resolution and in physics of turbulent plasma showed that real situation is much more complicated and standard approach is in contradiction both with observations and with problem of RTTCS stability. We present critical analysis of classic models of pre-flare energy accumulation and its dissipation during flare energy release from pioneer works Giovanelli (1939, 1947) up to topological reconnection. We show that all accepted description of global force-free fields as source of future flare cannot be agreed with discovered in last years fine and ultra-fine current-magnetic structure included numerouse arcs-threads with diameters up to 100 km with constant sequence from photosphere to corona. This magnetic skeleton of thin current magnetic threads with strong interaction between them is main source of reserved magnetic energy insolar atmosphere. Its dynamics will be controlled by percolation of magnetic stresses through network of current-magnetic threads with transition to flare state caused by critical value of global current. We show that thin turbulent current sheet is absolutely unstable configuration both caused by splitting to numerous linear currents by dissipative modes like to tearing, and as sequence of suppress of plasma turbulence caused by anomalous heating of turbulent plasma. In result of these factors primary RTTCS will be disrupted in numerous turbulent and normal plasma domains like to resistors network. Current propagation through this network will have percolation character with all accompanied properties of percolated systems: self-organization with formation power

  10. Flaring versus thermal incineration of waste gases in the oil and gas industry

    International Nuclear Information System (INIS)

    Smolarski, G.M.

    1999-01-01

    The efficient combustion of waste gases at oil processing plants, battery or well sites is discussed. Several problem situations are examined, field test results are reviewed, and custom design systems are explained including modifications to systems to conserve fuel. It is shown that combustion of waste gases in fuel efficient thermal incinerators is a practical means of disposal, particularly for sour or toxic gas of low heating value. These gases contain noxious compounds that may cause odours or adverse health effects. Results of a field tests of a portable in-situ incinerator show that compared to flaring (to oxide waste gas), incineration is a more efficient form of waste management. Emission tests also prove the superior performance of incineration. The feasibility of incinerating oil storage tank vapours was also demonstrated. Tests were also conducted with a fuel-efficient Glycol Still Off-Gas Incinerator which was developed to control toxic waste emissions. Glycol dehydration removes water vapour from natural gas. The key compounds that are removed by glycol are aromatic hydrocarbons or BTEX compounds (benzene, toluene, ethylbenzene and xylene), and sulphur compounds. The main design considerations for any incinerator are temperature, turbulence and residence time. An incinerator exit temperature of 760 degrees C is generally needed to reduce sulphur compounds. 2 refs., 8 tabs., 7 figs

  11. A magnetic bald-patch flare in solar active region 11117

    Science.gov (United States)

    Jiang, Chao-Wei; Feng, Xue-Shang; Wu, Shi-Tsan; Hu, Qiang

    2017-09-01

    With SDO observations and a data-constrained magnetohydrodynamics (MHD) model, we identify a confined multi-ribbon flare that occurred on 2010 October 25 in solar active region 11117 as a magnetic bald patch (BP) flare with strong evidence. From the photospheric magnetic field observed by SDO/HMI, we find there are indeed magnetic BPs on the polarity inversion lines (PILs) which match parts of the flare ribbons. From the 3D coronal magnetic field derived from an MHD relaxation model constrained by the vector magnetograms, we find strikingly good agreement of the BP separatrix surface (BPSS) footpoints with the flare ribbons, and the BPSS itself with the hot flaring loop system. Moreover, the triggering of the BP flare can be attributed to a small flux emergence under the lobe of the BPSS, and the relevant change of coronal magnetic field through the flare is reproduced well by the pre-flare and post-flare MHD solutions, which match the corresponding pre- and post-flare AIA observations, respectively. Our work contributes to the study of non-typical flares that constitute the majority of solar flares but which cannot be explained by the standard flare model.

  12. Increased productivity through waste reduction effort in oil and gas company

    Science.gov (United States)

    Hidayati, J.; Silviana, NA; Matondang, RA

    2018-02-01

    National companies engaged in oil and gas activities in the upstream sector. In general, the on going operations include drilling, exploration, and production activities with the result being crude oil channelled for shipment. Production activities produce waste gas (flare) of 0.58 MMSCFD derived from 17.05% of natural gas produced. Gas flares are residual gases that have been burning through flare stacks to avoid toxic gases such as H2S and CO that are harmful to human health and the environment. Therefore, appropriate environmental management is needed; one of them is by doing waste reduction business. Through this approach, it is expected that waste reduction efforts can affect the improvement of environmental conditions while increasing the productivity of the company. In this research begins by identifying the existence of problems on the company related to the amount of waste that is excessive and potentially to be reduced. Alternative improvements are then formulated and selected by their feasibility to be implemented through financial analysis, and the estimation of alternative contributions to the level of productivity. The result of this research is an alternative solution to solve the problem of the company by doing technological based engineering by reusing gas flare into fuel for incinerator machine. This alternative contributes to the increased productivity of material use by 23.32%, humans 83.8%, capital 10.13 %, and waste decreased by 0.11%.

  13. A water column study of methane around gas flares located at the West Spitsbergen continental margin

    DEFF Research Database (Denmark)

    Gentz, Torben; Damm, Ellen; von Deimling, Jens Schneider

    2014-01-01

    L1. Our results suggest that the methane dissolved from gas bubbles is efficiently trapped below the pycnocline and thus limits the methane concentration in surface water and the air–sea exchange during summer stratification. During winter the lateral stratification breaks down and fractions...... and ebullition of methane into the water column at more than 250 sites in an area of 665 km2. We conducted a detailed study of a subregion of this area, which covers an active gas ebullition area of 175 km2 characterized by 10 gas flares reaching from the seafloor at ∼245 m up to 50 m water depth to identify...... in the δ13CCH4 values point to a 13C depleted methane source (∼ –60‰ VPDB) being mainly mixed with a background values of the ambient water (∼–37.5‰ VPDB). A gas bubble dissolution model indicates that ∼80% of the methane released from gas bubbles into the ambient water takes place below the pycnocline...

  14. Gas exploitation and gas conversion; Gassutnyttelse og gasskonvertering

    Energy Technology Data Exchange (ETDEWEB)

    Laading, Gjert

    1998-07-01

    This presentation deals with some of the challenges and possibilities connected with ''stranded'' gas. These are offshore gas reserves, especially associated gas, that is not connected with the market and that cannot be piped onshore, and where reinjection is not profitable, and where flaring off is not an option. There is increasing interest all over the world to find economical and environmentally friendly solutions to this problem. A good solution will render such fields economically developable and will to a high degree increase the total volume of the world's exploitable gas reserves. Since synthesis gas is a dominating cost element in most chemical conversion processes for gas, the synthesis gases are discussed in some detail. There is also a discussion of the conversion of the gas to Methanol, Synthetic oil (Syncrude and Synfuels) and to DME (Di-methyl-ether). Two methods for gas transport from the field are discussed; LNG on floating production storage and off loading (FPSO), and Gas hydrates. Principles, limitations and conditions for placing those processes on a FPSO. Finally, the presentation discusses the most important economic factors related to the exploitation of offshore gas, and suggests some possibilities for future development.11 figs.

  15. Evidence for solar flare rare gases in the Khor Temiki aubrite.

    Science.gov (United States)

    Rajan, R. S.; Price, P. B.

    1973-01-01

    It has been found by studying a number of gas-rich meteorites, including Khor Temiki that there is a correlation between the abundance of 'track-rich' grains and the concentration of trapped rare gases. The amount of solar flare gas in Khor Temiki is examined. It is pointed out that the Khor Temiki enstatite is an ideal sample in which to look for evidence of solar flare gases because there has been little or no diffusion loss of solar wind gases.

  16. Solar flares

    International Nuclear Information System (INIS)

    Zirin, H.

    1974-01-01

    A review of the knowledge about solar flares which has been obtained through observations from the earth and from space by various methods is presented. High-resolution cinematography is best carried out at H-alpha wavelengths to reveal the structure, time history, and location of flares. The classification flares in H alpha according to either physical or morphological criteria is discussed. The study of flare morphology, which shows where, when, and how flares occur, is important for evaluating theories of flares. Consideration is given to studies of flares by optical spectroscopy, radio emissions, and at X-ray and XUV wavelengths. Research has shown where and possibly why flares occur, but the physics of the instability involved, of the particle acceleration, and of the heating are still not understood. (IAA)

  17. Design of emergency relief system to flare; Projeto de sistemas de alivio de emergencia para tocha

    Energy Technology Data Exchange (ETDEWEB)

    Britto, Joelson de Carvalho [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    The relief system has for objective to protect the unit equipment and piping system for high pressures developed during eventual operational upset. As examples of operational upset could mention: human failure (operational mistake - example: inadvertent closure of a block valve), heat exchange tube rupture, utility failure (cooling water, electric power, steam, instrument air) and fire. The relieved products are piping to flare system in order to burn the waste gas. The burned or unburned relieved stream shall be dispersed in order to not to cause damages to the people and the environment. That system should operate automatically without the need of interference of the personnel of the operation. The system is basically constituted of Pressure Safety and Relief Valves (PSVs), piping net, gas-liquid separation vessel, separation vessel residual liquid pump (if necessary) and flare for burning waste gas without liquid. They are necessary also some utilities as fuel gas (to be used as purge gas by flare tip and as fuel gas by pilots in order to guarantee the continuous operation of the flare pilots), electric power, instrument/service air and compressed air or steam (if necessary) to improve the quality of the burns. (author)

  18. Flare stars

    International Nuclear Information System (INIS)

    Nicastro, A.J.

    1981-01-01

    The least massive, but possibly most numerous, stars in a galaxy are the dwarf M stars. It has been observed that some of these dwarfs are characterized by a short increase in brightness. These stars are called flare stars. These flare stars release a lot of energy in a short amount of time. The process producing the eruption must be energetic. The increase in light intensity can be explained by a small area rising to a much higher temperature. Solar flares are looked at to help understand the phenomenon of stellar flares. Dwarfs that flare are observed to have strong magnetic fields. Those dwarf without the strong magnetic field do not seem to flare. It is believed that these regions of strong magnetic fields are associated with star spots. Theories on the energy that power the flares are given. Astrophysicists theorize that the driving force of a stellar flare is the detachment and collapse of a loop of magnetic flux. The mass loss due to stellar flares is discussed. It is believed that stellar flares are a significant contributor to the mass of interstellar medium in the Milky Way

  19. Estimates of global, regional, and national annual CO{sub 2} emissions from fossil-fuel burning, hydraulic cement production, and gas flaring: 1950--1992

    Energy Technology Data Exchange (ETDEWEB)

    Boden, T.A.; Marland, G. [Oak Ridge National Lab., TN (United States); Andres, R.J. [University of Alaska, Fairbanks, AK (United States). Inst. of Northern Engineering

    1995-12-01

    This document describes the compilation, content, and format of the most comprehensive C0{sub 2}-emissions database currently available. The database includes global, regional, and national annual estimates of C0{sub 2} emissions resulting from fossil-fuel burning, cement manufacturing, and gas flaring in oil fields for 1950--92 as well as the energy production, consumption, and trade data used for these estimates. The methods of Marland and Rotty (1983) are used to calculate these emission estimates. For the first time, the methods and data used to calculate CO, emissions from gas flaring are presented. This C0{sub 2}-emissions database is useful for carbon-cycle research, provides estimates of the rate at which fossil-fuel combustion has released C0{sub 2} to the atmosphere, and offers baseline estimates for those countries compiling 1990 C0{sub 2}-emissions inventories.

  20. Flare energetics

    Science.gov (United States)

    Wu, S. T.; Dejager, C.; Dennis, B. R.; Hudson, H. S.; Simnett, G. M.; Strong, K. T.; Bentley, R. D.; Bornmann, P. L.; Bruner, M. E.; Cargill, P. J.

    1986-01-01

    In this investigation of flare energetics, researchers sought to establish a comprehensive and self-consistent picture of the sources and transport of energy within a flare. To achieve this goal, they chose five flares in 1980 that were well observed with instruments on the Solar Maximum Mission, and with other space-borne and ground-based instruments. The events were chosen to represent various types of flares. Details of the observations available for them and the corresponding physical parameters derived from these data are presented. The flares were studied from two perspectives, the impulsive and gradual phases, and then the results were compared to obtain the overall picture of the energics of these flares. The role that modeling can play in estimating the total energy of a flare when the observationally determined parameters are used as the input to a numerical model is discussed. Finally, a critique of the current understanding of flare energetics and the methods used to determine various energetics terms is outlined, and possible future directions of research in this area are suggested.

  1. 40 CFR 65.147 - Flares.

    Science.gov (United States)

    2010-07-01

    ..., equal to or less than 122 meters per second (400 feet per second) if the net heating value of the gas... section, less than the velocity, V max, and less than 122 meters per second (400 feet per sec), where the... standard cubic meter (300 British thermal units per standard cubic foot) or greater if the flare is steam...

  2. The evolution of flaring and non-flaring active regions

    Science.gov (United States)

    Kilcik, A.; Yurchyshyn, V.; Sahin, S.; Sarp, V.; Obridko, V.; Ozguc, A.; Rozelot, J. P.

    2018-06-01

    According to the modified Zurich classification, sunspot groups are classified into seven different classes (A, B, C, D, E, F and H) based on their morphology and evolution. In this classification, classes A and B, which are small groups, describe the beginning of sunspot evolution, while classes D, E and F describe the large and evolved groups. Class C describes the middle phase of sunspot evolution and the class H describes the end of sunspot evolution. Here, we compare the lifetime and temporal evolution of flaring and non-flaring active regions (ARs), and the flaring effect on ARs in these groups in detail for the last two solar cycles (1996 through 2016). Our main findings are as follows: (i) Flaring sunspot groups have longer lifetimes than non-flaring ones. (ii) Most of the class A, B and C flaring ARs rapidly evolve to higher classes, while this is not applicable for non-flaring ARs. More than 50 per cent of the flaring A, B and C groups changed morphologically, while the remaining D, E, F and H groups did not change remarkably after the flare activity. (iii) 75 per cent of all flaring sunspot groups are large and complex. (iv) There is a significant increase in the sunspot group area in classes A, B, C, D and H after flaring activity. In contrast, the sunspot group area of classes E and F decreased. The sunspot counts of classes D, E and F decreased as well, while classes A, B, C and H showed an increase.

  3. A comparative study between clinical grading of anterior chamber flare and flare reading using the Kowa laser flare meter.

    Science.gov (United States)

    Konstantopoulou, Kallirroi; Del'Omo, Roberto; Morley, Anne M; Karagiannis, Dimitris; Bunce, Catey; Pavesio, Carlos

    2015-10-01

    To assess the accuracy of standard clinical grading of aqueous flare in uveitis according to the Standardization of Uveitis Nomenclature consensus, and compare the results with the readings of the laser flare meter, Kowa 500. Two examiners clinically graded the flare in 110 eyes. The flare was then measured using the Kowa laser flare meter. Twenty-nine eyes were graded as anterior chamber flare +2; for 18 of these, the clinicians were in agreement, the rest differed by the order of one grade. The range of the laser flare meter for these eyes was 5.2-899.1 photons/ms. The median value was 41.4. Seventy-four eyes were graded with flare +1. Agreement was established in 51 of these eyes. Disagreement for the rest was again by the order of 1, and the flare meter range was 1.1-169.9 photons/ms, median value 18.4. For the clinical measure of flare 0, the clinicians disagreed on three out of five eyes. The flare meter readings ranged from 2.5 to 14.1 photons/ms, median value 9.9. Only two eyes were graded with flare +3 and there was one step disagreement on both of them. We found little evidence of association between the flare readings and intraocular pressure or age. Our findings suggest that clinical evaluation of aqueous flare is subjective. Compared with the Kowa laser flare meter's numeric readings, the discrepancies observed indicate that clinical grading is an approximate science. The laser flare meter provides an accurate, reproducible, non-invasive assessment of aqueous flare that can prove valuable in research and clinical decisions.

  4. Flare-up rate of single-visit endodontics.

    Science.gov (United States)

    Trope, M

    1991-01-01

    The purpose of the study was to compare the flare-up rate for single-visit endodontics among teeth without radiographic or clinical signs of apical periodontitis, those with radiographic or clinical signs of apical periodontitis not previously root-treated, and those with apical periodontitis where retreatment was performed. All teeth were instrumented to a predetermined minimum size with a 0.5 per cent solution of sodium hypochlorite being used as the irrigant. The root canal was obturated without regard to the presence or absence of symptoms or diagnosis of the apical condition. The patients were given written post-operative instructions and a prescription for 600 mg ibuprofen to be taken if mild to moderate pain developed. If severe pain and/or swelling developed, the patient was instructed to telephone immediately and was considered to have had a flare-up. Teeth without signs of apical periodontitis did not have any flare-ups. One flare-up occurred in 69 teeth with signs of apical periodontitis not previously root-treated. The majority of the flare-ups (3 of 22 teeth) occurred in teeth with signs of apical periodontitis requiring retreatment.

  5. Solar flare neon and solar cosmic ray fluxes in the past using gas-rich meteorites

    International Nuclear Information System (INIS)

    Nautiyal, C.M.; Rao, M.N.

    1986-01-01

    Methods were developed earlier to deduce the composition of solar flare neon and to determine the solar cosmic ray proton fluxes in the past using etched lunar samples and at present, these techniques are extended to gas rich meteorites. By considering high temperature Ne data points for Pantar, Fayetteville and other gas rich meteorites and by applying the three component Ne-decomposition methods, the solar cosmic ray and galactic cosmic ray produced spallation Ne components from the trapped SF-Ne was resolved. Using appropiate SCR and GCR production rates, in the case of Pantar, for example, a GCR exposure age of 2 m.y. was estimated for Pantar-Dark while Pantar-Light yielded a GCR age of approx. 3 m.y. However the SCR exposure age of Pantar-Dark is two orders of magnitude higher than the average surface exposure ages of lunar soils. The possibility of higher proton fluxes in the past is discussed

  6. Deep Flare Net (DeFN) Model for Solar Flare Prediction

    Science.gov (United States)

    Nishizuka, N.; Sugiura, K.; Kubo, Y.; Den, M.; Ishii, M.

    2018-05-01

    We developed a solar flare prediction model using a deep neural network (DNN) named Deep Flare Net (DeFN). This model can calculate the probability of flares occurring in the following 24 hr in each active region, which is used to determine the most likely maximum classes of flares via a binary classification (e.g., ≥M class versus statistically predict flares, the DeFN model was trained to optimize the skill score, i.e., the true skill statistic (TSS). As a result, we succeeded in predicting flares with TSS = 0.80 for ≥M-class flares and TSS = 0.63 for ≥C-class flares. Note that in usual DNN models, the prediction process is a black box. However, in the DeFN model, the features are manually selected, and it is possible to analyze which features are effective for prediction after evaluation.

  7. Relationship of intracanal medicaments to endodontic flare-ups.

    Science.gov (United States)

    Trope, M

    1990-10-01

    The purpose of the study was to compare the effect of three intracanal medicaments on the incidence of post-instrumentation flare-ups. All teeth were instrumented to a predetermined minimum size using a 0.5% solution of sodium hypochlorite as the irrigant. Formocresol, Ledermix, and calcium hydroxide were placed in strict sequence irrespective of the presence or absence of symptoms or radiographic signs of apical periodontitis. The patients were given written post-operative instructions and a prescription for 600 mg ibuprofen to be taken if mild to moderate pain developed. If severe pain and/or swelling developed the patient was instructed to call the office immediately and was considered to have had a flare-up. Twelve flare-ups occurred in teeth with radiographic signs of apical periodontitis; none in teeth without periapical radiolucencies. Six of the twelve flare-ups occurred in retreatment cases and the other six occurred in teeth without previous endodontic treatment. No significant difference was found in the flare-up rate among the three intracanal medicaments.

  8. Associated petroleum gas in Russia: reasons for non-utilization

    Energy Technology Data Exchange (ETDEWEB)

    Roeland, Tonje Hulbak

    2010-10-22

    This report studies the factors hindering increased utilization of associated petroleum gas (APG) in Russia. The issue of flaring versus utilization is studied from a Technology Innovation System (TIS) perspective, seeing the non-utilization issue as a problem of technology diffusion. There are many technological options available for APG utilization, but a main blocking mechanism in the Russian case is the Gazprom monopoly on gas transportation via their pipelines. A commonly discussed solution is policy to ensure third party access, but this study finds that this solution holds little potential, as its ramifications are too extensive and unacceptable to the key actor Gazprom. More promising solutions may be found in small, emerging engineering companies. (Author)

  9. Spatially inhomogeneous acceleration of electrons in solar flares

    Science.gov (United States)

    Stackhouse, Duncan J.; Kontar, Eduard P.

    2018-04-01

    The imaging spectroscopy capabilities of the Reuven Ramaty high energy solar spectroscopic imager (RHESSI) enable the examination of the accelerated electron distribution throughout a solar flare region. In particular, it has been revealed that the energisation of these particles takes place over a region of finite size, sometimes resolved by RHESSI observations. In this paper, we present, for the first time, a spatially distributed acceleration model and investigate the role of inhomogeneous acceleration on the observed X-ray emission properties. We have modelled transport explicitly examining scatter-free and diffusive transport within the acceleration region and compare with the analytic leaky-box solution. The results show the importance of including this spatial variation when modelling electron acceleration in solar flares. The presence of an inhomogeneous, extended acceleration region produces a spectral index that is, in most cases, different from the simple leaky-box prediction. In particular, it results in a generally softer spectral index than predicted by the leaky-box solution, for both scatter-free and diffusive transport, and thus should be taken into account when modelling stochastic acceleration in solar flares.

  10. Methane, Black Carbon, and Ethane Emissions from Natural Gas Flares in the Bakken Shale, North Dakota.

    Science.gov (United States)

    Gvakharia, Alexander; Kort, Eric A; Brandt, Adam; Peischl, Jeff; Ryerson, Thomas B; Schwarz, Joshua P; Smith, Mackenzie L; Sweeney, Colm

    2017-05-02

    Incomplete combustion during flaring can lead to production of black carbon (BC) and loss of methane and other pollutants to the atmosphere, impacting climate and air quality. However, few studies have measured flare efficiency in a real-world setting. We use airborne data of plume samples from 37 unique flares in the Bakken region of North Dakota in May 2014 to calculate emission factors for BC, methane, ethane, and combustion efficiency for methane and ethane. We find no clear relationship between emission factors and aircraft-level wind speed or between methane and BC emission factors. Observed median combustion efficiencies for methane and ethane are close to expected values for typical flares according to the US EPA (98%). However, we find that the efficiency distribution is skewed, exhibiting log-normal behavior. This suggests incomplete combustion from flares contributes almost 1/5 of the total field emissions of methane and ethane measured in the Bakken shale, more than double the expected value if 98% efficiency was representative. BC emission factors also have a skewed distribution, but we find lower emission values than previous studies. The direct observation for the first time of a heavy-tail emissions distribution from flares suggests the need to consider skewed distributions when assessing flare impacts globally.

  11. Cold and hot model investigation of flow and mixing in a multi-jet flare

    Energy Technology Data Exchange (ETDEWEB)

    Pagot, P.R. [Petrobras Petroleo Brasileiro S.A., Rio de Janeiro (Brazil); Sobiesiak, A. [Windsor Univ., ON (Canada); Grandmaison, E.W. [Queen' s Univ., Kingston, ON (Canada). Centre for Advanced Gas Combustion Technology

    2003-07-01

    The oil and gas industry commonly disposes of hydrocarbon wastes by flaring. This study simulated several features of industrial offshore flares in a multi-jet burner. Cold and hot flow experiments were performed. Twenty-four nozzles mounted on radial arms originating from a central fuel plenum were used in the burner design. In an effort to improve the mixing and radiation characteristics of this type of burner, an examination of the effect of various mixing-altering devices on the nozzle exit ports was performed. Flow visualization studies of the cold and hot flow systems were presented, along with details concerning temperature, gas composition and radiation levels from the burner models. The complex flow pattern resulting when multiple jets are injected into a cross flow stream were demonstrated with the flow visualization studies from the cold model. The trajectory followed by the leading edge jet for the reference case and the ring attachments was higher but similar to the simple round jet in a cross flow. The precessing jets and the cone attachments were more strongly deflected by the cross flow with a higher degree of mixing between the jets in the nozzle region. For different firing rates, flow visualization, gas temperature, gas composition and radiative heat flux measurements were performed in the hot model studies. Flame trajectories, projected side view areas and volumes increased with firing rates for all nozzle configurations and the ring attachment flare had the smallest flame volume. The gas temperatures reached maximum values at close to 30 per cent of the flame length and the lowest gas temperature was observed for the flare model with precessing jets. For the reference case nozzle, nitrogen oxide (NOx) concentrations were in the 30 to 45 parts per million (ppm) range. The precessing jet model yielded NOx concentrations in the 22 to 24 ppm range, the lowest obtained. There was a linear dependence between the radiative heat flux from the flames

  12. The Effects of Flare Definitions on the Statistics of Derived Flare Distrubtions

    Science.gov (United States)

    Ryan, Daniel; Dominique, Marie; Seaton, Daniel B.; Stegen, Koen; White, Arthur

    2016-05-01

    The statistical examination of solar flares is crucial to revealing their global characteristics and behaviour. However, statistical flare studies are often performed using standard but basic flare detection algorithms relying on arbitrary thresholds which may affect the derived flare distributions. We explore the effect of the arbitrary thresholds used in the GOES event list and LYRA Flare Finder algorithms. We find that there is a small but significant relationship between the power law exponent of the GOES flare peak flux frequency distribution and the algorithms’ flare start thresholds. We also find that the power law exponents of these distributions are not stable but appear to steepen with increasing peak flux. This implies that the observed flare size distribution may not be a power law at all. We show that depending on the true value of the exponent of the flare size distribution, this deviation from a power law may be due to flares missed by the flare detection algorithms. However, it is not possible determine the true exponent from GOES/XRS observations. Additionally we find that the PROBA2/LYRA flare size distributions are clearly non-power law. We show that this is consistent with an insufficient degradation correction which causes LYRA absolute irradiance values to be unreliable. This means that they should not be used for flare statistics or energetics unless degradation is adequately accounted for. However they can be used to study time variations over shorter timescales and for space weather monitoring.

  13. Solar flares

    International Nuclear Information System (INIS)

    Kaastra, J.S.

    1985-01-01

    In this thesis an electrodynamic model for solar flares is developed. The main theoretical achievements underlying the present study are treated briefly and the observable flare parameters are described within the framework of the flare model of this thesis. The flare model predicts large induced electric fields. Therefore, acceleration processes of charged particles by direct electric fields are treated. The spectrum of the accelerated particles in strong electric fields is calculated, 3 with the electric field and the magnetic field perpendicular and in the vicinity of an X-type magnetic neutral line. An electromagnetic field configuration arises in the case of a solar flare. A rising current filament in a quiescent background bipolar magnetic field causes naturally an X-type magnetic field configuration below the filament with a strong induced electric field perpendicular to the ambient magnetic field. This field configuration drives particles and magnetic energy towards the neutral line, where a current sheet is generated. The global evolution of the fields in the flare is determined by force balance of the Lorentz forces on the filament and the force balance on the current sheet. The X-ray, optical and radio observations of a large solar flare on May 16, 1981 are analyzed. It is found that these data fit the model very well. (Auth.)

  14. KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States); Hebb, Leslie [Department of Physics, Hobart and William Smith Colleges, 300 Pulteney Street, Geneva, NY 14456 (United States); Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R. [HL Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks Street, Norman, OK 73019 (United States); Kowalski, Adam F. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Hilton, Eric J., E-mail: jrad@astro.washington.edu [Universe Sandbox, 911 E. Pike Street #333, Seattle, WA 98122 (United States)

    2014-12-20

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10{sup 29} to 10{sup 33} erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.

  15. KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243

    International Nuclear Information System (INIS)

    Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M.; Hebb, Leslie; Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R.; Kowalski, Adam F.; Hilton, Eric J.

    2014-01-01

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10 29 to 10 33 erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events

  16. Numerical simulations of flares on M dwarf stars. I - Hydrodynamics and coronal X-ray emission

    Science.gov (United States)

    Cheng, Chung-Chieh; Pallavicini, Roberto

    1991-01-01

    Flare-loop models are utilized to simulate the time evolution and physical characteristics of stellar X-ray flares by varying the values of flare-energy input and loop parameters. The hydrodynamic evolution is studied in terms of changes in the parameters of the mass, energy, and momentum equations within an area bounded by the chromosphere and the corona. The zone supports a magnetically confined loop for which processes are described including the expansion of heated coronal gas, chromospheric evaporation, and plasma compression at loop footpoints. The intensities, time profiles, and average coronal temperatures of X-ray flares are derived from the simulations and compared to observational evidence. Because the amount of evaporated material does not vary linearly with flare-energy input, large loops are required to produce the energy measured from stellar flares.

  17. Solution of Riemann problem for ideal polytropic dusty gas

    International Nuclear Information System (INIS)

    Nath, Triloki; Gupta, R.K.; Singh, L.P.

    2017-01-01

    Highlights : • A direct approach is used to solve the Riemann problem for dusty ideal polytropic gas. • An analytical solution to the Riemann problem for dusty gas flow is obtained. • The existence and uniqueness of the solution in dusty gas is discussed. • Properties of elementary wave solutions of Riemann problem are discussed. • Effect of mass fraction of solid particles on the solution is presented. - Abstract: The Riemann problem for a quasilinear hyperbolic system of equations governing the one dimensional unsteady flow of an ideal polytropic gas with dust particles is solved analytically without any restriction on magnitude of the initial states. The elementary wave solutions of the Riemann problem, that is shock waves, rarefaction waves and contact discontinuities are derived explicitly and their properties are discussed, for a dusty gas. The existence and uniqueness of the solution for Riemann problem in dusty gas is discussed. Also the conditions leading to the existence of shock waves or simple waves for a 1-family and 3-family curves in the solution of the Riemann problem are discussed. It is observed that the presence of dust particles in an ideal polytropic gas leads to more complex expression as compared to the corresponding ideal case; however all the parallel results remain same. Also, the effect of variation of mass fraction of dust particles with fixed volume fraction (Z) and the ratio of specific heat of the solid particles and the specific heat of the gas at constant pressure on the variation of velocity and density across the shock wave, rarefaction wave and contact discontinuities are discussed.

  18. Flare Observations

    Directory of Open Access Journals (Sweden)

    Benz Arnold O.

    2008-02-01

    Full Text Available Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays at 100 MeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, and SOHO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections (CMEs, electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting reconnection of magnetic field lines as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth’s lower ionosphere. While flare scenarios have slowly converged over the past decades, every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

  19. Flare Observations

    Science.gov (United States)

    Benz, Arnold O.

    2017-12-01

    Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays beyond 1 GeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, SOHO, and more recently Hinode and SDO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections, electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s) of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting magnetic reconnection as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth's ionosphere. Flare scenarios have slowly converged over the past decades, but every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

  20. On the possible cyclic recurrence of flare activity of flare stars in the pleiades

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.; Oganyan, G.V.

    1977-01-01

    The flare activity of flare stars in Pleiades is investigated. It is shown that according to flare statistics only one half of the probable Pleiades members with low luminosities have flare activity throughout the observation period. Two assumptions are suggested to explain this contradiction with the concept on the evolutionary importance of the flare star phase which all the dwarf stars go through: cyclic nature of the flare activity and large dispersion in flare activity phase durations for equally luminous stars. Certain evidences to support cyclic flare activity assumption are adduced

  1. Fibromyalgia Flares: A Qualitative Analysis.

    Science.gov (United States)

    Vincent, Ann; Whipple, Mary O; Rhudy, Lori M

    2016-03-01

    Patients with fibromyalgia report periods of symptom exacerbation, colloquially referred to as "flares" and despite clinical observation of flares, no research has purposefully evaluated the presence and characteristics of flares in fibromyalgia. The purpose of this qualitative study was to describe fibromyalgia flares in a sample of patients with fibromyalgia. Using seven open-ended questions, patients were asked to describe how they perceived fibromyalgia flares and triggers and alleviating factors associated with flares. Patients were also asked to describe how a flare differs from their typical fibromyalgia symptoms and how they cope with fibromyalgia flares. Content analysis was used to analyze the text. A total of 44 participants completed the survey. Responses to the seven open-ended questions revealed three main content areas: causes of flares, flare symptoms, and dealing with a flare. Participants identified stress, overdoing it, poor sleep, and weather changes as primary causes of flares. Symptoms characteristic of flares included flu-like body aches/exhaustion, pain, fatigue, and variety of other symptoms. Participants reported using medical treatments, rest, activity and stress avoidance, and waiting it out to cope with flares. Our results demonstrate that periods of symptom exacerbation (i.e., flares) are commonly experienced by patients with fibromyalgia and symptoms of flares can be differentiated from every day or typical symptoms of fibromyalgia. Our study is the first of its kind to qualitatively explore characteristics, causes, and management strategies of fibromyalgia flares. Future studies are needed to quantitatively characterize fibromyalgia flares and evaluate mechanisms of flares. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Implications of NRL/ATM solar flare observations on flare theories

    International Nuclear Information System (INIS)

    Cheng, C.C.; Spicer, D.S.

    1975-01-01

    During the Skylab mission, many solar flares were observed with the NRL XUV spectroheliogram in the wavelength region from 150 to 650 A. Because of its high spatial resolution (approximately 2ins.) the three-dimensional structures of the flare emission regions characterized by temperatures from 10 4 K to 20 x 10 6 K can be resolved. Thus the spatial relationship between the relatively cool plasma and the hot plasma components of a flare, and the associated magnetic field structure can be inferred. The implications for various flare models are discussed. (Auth.)

  3. Statistical study of spatio-temporal distribution of precursor solar flares associated with major flares

    Science.gov (United States)

    Gyenge, N.; Ballai, I.; Baranyi, T.

    2016-07-01

    The aim of the present investigation is to study the spatio-temporal distribution of precursor flares during the 24 h interval preceding M- and X-class major flares and the evolution of follower flares. Information on associated (precursor and follower) flares is provided by Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Flare list, while the major flares are observed by the Geostationary Operational Environmental Satellite (GOES) system satellites between 2002 and 2014. There are distinct evolutionary differences between the spatio-temporal distributions of associated flares in about one-day period depending on the type of the main flare. The spatial distribution was characterized by the normalized frequency distribution of the quantity δ (the distance between the major flare and its precursor flare normalized by the sunspot group diameter) in four 6 h time intervals before the major event. The precursors of X-class flares have a double-peaked spatial distribution for more than half a day prior to the major flare, but it changes to a lognormal-like distribution roughly 6 h prior to the event. The precursors of M-class flares show lognormal-like distribution in each 6 h subinterval. The most frequent sites of the precursors in the active region are within a distance of about 0.1 diameter of sunspot group from the site of the major flare in each case. Our investigation shows that the build-up of energy is more effective than the release of energy because of precursors.

  4. Solutions to operate transmission and distribution gas networks

    Directory of Open Access Journals (Sweden)

    Neacsu Sorin

    2017-01-01

    Full Text Available In order to respect the actual and future regulations, besides SCADA, there is a need for further modern operating solutions for the transmission and distribution gas network. The paper presents the newest operating principles and modern software solutions that represent a considerable help to operate the transmission and distribution gas networks.

  5. Flare stars in Pleiades. 6

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.; Chavushyan, O.S.; Oganyan, G.B.; Ambaryan, V.V.; Garibdzhanyan, A.T.; Melikyan, N.D.; Natsvlishvili, R.Sh.; AN Gruzinskoj SSR, Abastumani. Abastumanskaya Astrofizicheskaya Observatoriya)

    1981-01-01

    The results of photographic observations of stellar flares in the Pleiades region carried out at the Byurakan and Abastumani astrophysical observatories during 1976-1979 are given. On the basis of these observations 17 new flare stars have been found. Total number of all known flare stars in the Pleiades region on 1 June 1980 reached 524, and the number of all flares-1244. The observational data on distribution of flare stars according to the observed flares is satisfactorily represented by the average frequency function introduced by V.A.Ambartsumian. The total number of the flare stars in the Pleiades is of the order of 1100. Using three telescopes, synchronous photographic observations of stellar flares in Pleiades in U, B, V, system are carried out. The colour indices U-B and B-V of stellar flares in periods including the maximum of the flare slightly differ from that of photoelectrically defined for flares of UV Ceti type stars, which testifies the physical relationship of flare stars in Pleiades and in the vicinity of the Sun [ru

  6. Temporal and Periodic Variations of Sunspot Counts in Flaring and Non-Flaring Active Regions

    Science.gov (United States)

    Kilcik, A.; Yurchyshyn, V.; Donmez, B.; Obridko, V. N.; Ozguc, A.; Rozelot, J. P.

    2018-04-01

    We analyzed temporal and periodic variations of sunspot counts (SSCs) in flaring (C-, M-, or X-class flares), and non-flaring active regions (ARs) for nearly three solar cycles (1986 through 2016). Our main findings are as follows: i) temporal variations of monthly means of the daily total SSCs in flaring and non-flaring ARs behave differently during a solar cycle and the behavior varies from one cycle to another; during Solar Cycle 23 temporal SSC profiles of non-flaring ARs are wider than those of flaring ARs, while they are almost the same during Solar Cycle 22 and the current Cycle 24. The SSC profiles show a multi-peak structure and the second peak of flaring ARs dominates the current Cycle 24, while the difference between peaks is less pronounced during Solar Cycles 22 and 23. The first and second SSC peaks of non-flaring ARs have comparable magnitude in the current solar cycle, while the first peak is nearly absent in the case of the flaring ARs of the same cycle. ii) Periodic variations observed in the SSCs profiles of flaring and non-flaring ARs derived from the multi-taper method (MTM) spectrum and wavelet scalograms are quite different as well, and they vary from one solar cycle to another. The largest detected period in flaring ARs is 113± 1.6 days while we detected much longer periodicities (327± 13, 312 ± 11, and 256± 8 days) in the non-flaring AR profiles. No meaningful periodicities were detected in the MTM spectrum of flaring ARs exceeding 55± 0.7 days during Solar Cycles 22 and 24, while a 113± 1.3 days period was detected in flaring ARs of Solar Cycle 23. For the non-flaring ARs the largest detected period was only 31± 0.2 days for Cycle 22 and 72± 1.3 days for the current Cycle 24, while the largest measured period was 327± 13 days during Solar Cycle 23.

  7. Contribution of Tula Refinery flaring emissions to the Mexico megacity

    Science.gov (United States)

    Almanza, Victor; Molina, Luisa; Sosa, Gustavo

    2013-04-01

    Flaring is an important source of greenhouse gases, particulate matter and Volatile Organic Compounds (VOCs) in both upstream and downstream operations in the oil and gas industry. In 2010 Mexico was the eleventh emitting country with 2.5 billion cubic meters of gas flared (World Bank, 2012). Black carbon (a component of soot) emissions from flaring facilities are of particular interest because soot is considered a short-lived climate forcer (SLCF) (UNEP, 2011). In 2011 there were 23 megacities of at least 10 million inhabitants. It is expected that this number increase to 37 by 2025, which will include one more in Northern America (NA) and two more in Latin America (UN, 2012). International collaborative projects like MILAGRO in NA and MEGAPOLI/CityZen in Europe, have been conducted to assess the impact of megacities air pollution at several scales. The former focused on the air pollution plume of Mexico City Metropolitan Area (MCMA), the largest megacity in NA. This work studies the contribution of flaring emissions from Tula Refinery to regional air quality. This is accomplished in two steps. First, the flame of a representative sour gas flare is modeled with a CFD combustion code in order to estimate emission rates of combustion by-products of interest for air quality. Mass flow rates of acetylene, ethylene, nitrogen oxides, carbon monoxide, soot and sulfur dioxide are obtained. The emission rates of NO2 and SO2 are compared with measurements obtained at Tula as part of MILAGRO field campaign. The rates of soot, VOCs and CO emissions are compared with estimates obtained by Instituto Mexicano del Petróleo (IMP). The second stage takes the flaring emission rates of the aforementioned species as inputs to WRF-Chem in order to simulate the chemical transport of the plume from 22 March to 27 March of 2006. The air quality model presented reliable performance of the resolved meteorology, with respect to the Mean Absolute Error (MAE), Root Mean Square Error (RMSE

  8. Solar Flares: Magnetohydrodynamic Processes

    Directory of Open Access Journals (Sweden)

    Kazunari Shibata

    2011-12-01

    Full Text Available This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 10^32 erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence, local enhancement of electric current in the corona (formation of a current sheet, and rapid dissipation of electric current (magnetic reconnection that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely, while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.

  9. Models for stellar flares

    International Nuclear Information System (INIS)

    Cram, L.E.; Woods, D.T.

    1982-01-01

    We study the response of certain spectral signatures of stellar flares (such as Balmer line profiles and the broad-band continuum) to changes in atmospheric structure which might result from physical processes akin to those thought to occur in solar flares. While each physical process does not have a unique signature, we can show that some of the observed properties of stellar flares can be explained by a model which involves increased pressures and temperatures in the flaring stellar chromosphere. We suggest that changes in stellar flare area, both with time and with depth in the atmosphere, may play an important role in producing the observed flare spectrum

  10. Flare stars in Pleiades. 5

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.; Chavushyan, O.S.; Erastova, L.K.; Oganyan, G.B.; Melikyan, N.D.; Natsvlishvili, R.Sh.; Tsvetkov, M.K.

    1977-01-01

    The results of photographic observations of stellar flares in the Pleiades region made in the Byurakan and Abastumany astrophysical observatories in 1973-1974 are presented. The observations and revisions of the pictures taken earlier helped to detect 20 new flare stars and 62 repeated flares of flare stars known before. Two-colour photographic and UV observation of 21 flares were carried out. The observation data point to considerable differences in the mean frequency of flares of various flare stars in the Pleiades

  11. Elongation of Flare Ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman MT (United States); Cassak, Paul A. [Department of Physics and Astronomy, West Virginia University, Morgantown WV (United States); Priest, Eric R. [School of Mathematics and Statistics, University of St. Andrews, Fife KY16 9SS, Scotland (United Kingdom)

    2017-03-20

    We present an analysis of the apparent elongation motion of flare ribbons along the polarity inversion line (PIL), as well as the shear of flare loops in several two-ribbon flares. Flare ribbons and loops spread along the PIL at a speed ranging from a few to a hundred km s{sup −1}. The shear measured from conjugate footpoints is consistent with the measurement from flare loops, and both show the decrease of shear toward a potential field as a flare evolves and ribbons and loops spread along the PIL. Flares exhibiting fast bidirectional elongation appear to have a strong shear, which may indicate a large magnetic guide field relative to the reconnection field in the coronal current sheet. We discuss how the analysis of ribbon motion could help infer properties in the corona where reconnection takes place.

  12. Chandra Captures Flare From Brown Dwarf

    Science.gov (United States)

    2000-07-01

    only 16 light years from Earth. The absence of X-rays from LP 944-20 during the non-flaring period is in itself a significant result. It sets the lowest limit on steady X-ray power produced by a brown dwarf, and shows that the million degree Celsius upper atmospheres, or coronas, cease to exist as the surface temperature of a brown dwarf cools below about 2500 degrees Celsius. "This is an important confirmation of the trend that hot gas in the atmospheres of lower mass stars is produced only in flares," said Professor Lars Bildsten of the University of California, Santa Barbara, also a member of the team. Brown dwarfs have too little mass to sustain significant nuclear reactions in their cores. Their primary source of energy is the release of gravitational energy as they slowly contract. They are very dim ­ less than a tenth of a percent as luminous as the Sun -- and of great interest to astronomers because they are poorly understood and probably a very common class of objects that are intermediate between normal stars and giant planets. The 12-hour observation of LP 944-20 was made on December 15, 1999, using the Advanced CCD Imaging Spectrometer (ACIS). The ACIS instrument was built for NASA by the Massachusetts Institute of Technology, Cambridge, and Pennsylvania State University, University Park. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass. Images associated with this release are available on the World Wide Web at: http://chandra.harvard.edu AND http://chandra.nasa.gov High resolution digital versions of the X-ray image (JPG, 300 dpi TIFF) are available at the Internet sites listed above.

  13. Magnetic transients in flares

    International Nuclear Information System (INIS)

    Zirin, H.; Tanaka, K.

    1981-01-01

    We present data on magnetic transients (mgtr's) observed in flares on 1980 July 1 and 5 with Big Bear videomagnetograph (VMG). The 1980 July 1 event was a white light flare in which a strong bipolar mgtr was observed, and a definite change in the sunspots occurred at the time of the flare. In the 1980 July 5 flare, a mgtr was observed in only one polarity, and, although no sunspot changes occurred simultaneous with the flare, major spot changes occurred in a period of hours

  14. Recent big flare

    International Nuclear Information System (INIS)

    Moriyama, Fumio; Miyazawa, Masahide; Yamaguchi, Yoshisuke

    1978-01-01

    The features of three big solar flares observed at Tokyo Observatory are described in this paper. The active region, McMath 14943, caused a big flare on September 16, 1977. The flare appeared on both sides of a long dark line which runs along the boundary of the magnetic field. Two-ribbon structure was seen. The electron density of the flare observed at Norikura Corona Observatory was 3 x 10 12 /cc. Several arc lines which connect both bright regions of different magnetic polarity were seen in H-α monochrome image. The active region, McMath 15056, caused a big flare on December 10, 1977. At the beginning, several bright spots were observed in the region between two main solar spots. Then, the area and the brightness increased, and the bright spots became two ribbon-shaped bands. A solar flare was observed on April 8, 1978. At first, several bright spots were seen around the solar spot in the active region, McMath 15221. Then, these bright spots developed to a large bright region. On both sides of a dark line along the magnetic neutral line, bright regions were generated. These developed to a two-ribbon flare. The time required for growth was more than one hour. A bright arc which connects two ribbons was seen, and this arc may be a loop prominence system. (Kato, T.)

  15. Identifying flares in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Bykerk, Vivian P; Bingham, Clifton O; Choy, Ernest H

    2016-01-01

    to flare, with escalation planned in 61%. CONCLUSIONS: Flares are common in rheumatoid arthritis (RA) and are often preceded by treatment reductions. Patient/MD/DAS agreement of flare status is highest in patients worsening from R/LDA. OMERACT RA flare questions can discriminate between patients with...... Set. METHODS: Candidate flare questions and legacy measures were administered at consecutive visits to Canadian Early Arthritis Cohort (CATCH) patients between November 2011 and November 2014. The American College of Rheumatology (ACR) core set indicators were recorded. Concordance to identify flares...

  16. The evaluation of endodontic flare-ups and their relationship to various risk factors.

    Science.gov (United States)

    Onay, Emel Olga; Ungor, Mete; Yazici, A Canan

    2015-11-14

    To evaluate the incidence of flare-ups and identify the risk factors including age, gender, tooth type, number of root canals, initial diagnosis, the type of irrigation regimen, treatment modality and the number of visits, in patients who received root canal treatment from January 2002 to January 2008. Records of 1819 teeth belonging to 1410 patients treated by 1 endodontics specialist during 6-year period were kept. Patient, tooth, and treatment characteristics were evaluated and the relationships between these characteristics and flare-ups were studied. Statistical analysis was carried out by using Pearson Chi-square test, Fisher's Exact test, and Binary Logistic regression analyses. The incidence of flare-ups was 59 (3.2 %) out of 1819 teeth that received endodontic therapy. Pulpal necrosis without periapical pathosis was the most common indication for flare-up (6 %) (p flare-ups compared to those with single appointments (OR: 3.14, CI: 1.414-7.009, p flare-ups regarding to age, gender, tooth type, number of root canals, treatment modality, and the irrigation solutions that used during the treatment. The incidence of flare-up is minimal when teeth are treated in one visit. Absence of a periapical lesion in necrotic teeth is a significant risk factor for flare-ups.

  17. Solar flare impulsivity and its relationship with white-light flares and with CMEs

    Science.gov (United States)

    Watanabe, K.; Masuda, S.

    2017-12-01

    There are many types of classification in solar flares. One of them is a classification by flare duration in soft X-rays; so-called impulsive flare and long duration event (LDE). Typically, the duration of an impulsive flare is shorter than 1 hour, and that of an LDE is longer than 1 hour. These two types of flare show different characteristics. In soft X-rays, impulsive flares usually have a compact loop structure. On the other hand, LDEs show a large-scale loop, sometimes a large arcade structure. In hard X-rays (HXRs), the difference appears clear, too. The former shows a strong and short-time (10 minutes) emissions and show a large coronal source. These facts suggest that HXR observation becomes one of a good indicator to classify solar flares, especially for the study on the particle acceleration and the related phenomena. However, HXR data do not always exist due to the satellite orbit and the small sensitivity of HXR instruments. So, in this study, based on the concept of the Neupert effect (Neupert, 1968), we use soft X-ray derivative data as the proxy of HXR. From this data, we define impulsivity (IP) for each flare. Then we investigate solar flares using this new index. First we apply IP index to white-light flare (WLF) research. We investigate how WL enhancement depends on IP, then it is found that WLF tend to have large IP values. So the flare impulsivity (IP) is one of the important factors if WL enhancement appears or not in a solar flare. Next we investigate how CME itself and/or its physical parameters depend on IP index. It has been believed that most of CMEs are associated with LDEs, but we found that there is only a weak correlation between the existence of CME and IP index. Finally, we also search for the relationship between WLF and CME as a function of IP and discuss the physical condition of WLF.

  18. Visualization of Solution Gas Drive in Viscous Oil, SUPRI TR-126

    Energy Technology Data Exchange (ETDEWEB)

    George, D.S.; Kovscek, A.R.

    2001-07-23

    Several experimental studies of solution gas drive are available in this report. Almost all of the studies have used light oil. Solution gas drive behavior, especially in heavy oil reservoirs, is poorly understood. Experiments were performed in which pore-scale solution gas drive phenomena were viewed in water/carbon dioxide and viscous oil/carbon dioxide systems. A new pressure vessel was designed and constructed to house silicon-wafer micromodels that previously operated at low (<3 atm) pressure. The new apparatus is used for the visual studies. Several interesting phenomena were viewed. The repeated nucleation of gas bubbles was observed at a gas-wet site occupied by dirt. Interestingly, the dissolution of a gas bubble into the liquid phase was previously recorded at the same nucleation site. Gas bubbles in both systems grew to span one ore more pore bodies before mobilization. Liquid viscosity affected the ease with which gas bubbles coalesced. More viscous solutions result in slower rates of coalescence. The transport of solid particles on gas-liquid interfaces was also observed.

  19. Which of Kepler's Stars Flare?

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    The habitability of distant exoplanets is dependent upon many factors one of which is the activity of their host stars. To learn about which stars are most likely to flare, a recent study examines tens of thousands of stellar flares observed by Kepler.Need for a Broader SampleArtists rendering of a flaring dwarf star. [NASAs Goddard Space Flight Center/S. Wiessinger]Most of our understanding of what causes a star to flare is based on observations of the only star near enough to examine in detail the Sun. But in learning from a sample size of one, a challenge arises: we must determine which conclusions are unique to the Sun (or Sun-like stars), and which apply to other stellar types as well.Based on observations and modeling, astronomers think that stellar flares result from the reconnection of magnetic field lines in a stars outer atmosphere, the corona. The magnetic activity is thought to be driven by a dynamo caused by motions in the stars convective zone.HR diagram of the Kepler stars, with flaring main-sequence (yellow), giant (red) and A-star (green) stars in the authors sample indicated. [Van Doorsselaere et al. 2017]To test whether these ideas are true generally, we need to understand what types of stars exhibit flares, and what stellar properties correlate with flaring activity. A team of scientists led by Tom Van Doorsselaere (KU Leuven, Belgium) has now used an enormous sample of flares observed by Kepler to explore these statistics.Intriguing TrendsVan Doorsselaere and collaborators used a new automated flare detection and characterization algorithm to search through the raw light curves from Quarter 15 of the Kepler mission, building a sample of 16,850 flares on 6,662 stars. They then used these to study the dependence of the flare occurrence rate, duration, energy, and amplitude on the stellar spectral type and rotation period.This large statistical study led the authors to several interesting conclusions, including:Flare star incidence rate as a a

  20. Prediction of flare activity of stellar aggregates. I. Theoretical part

    International Nuclear Information System (INIS)

    Mnatsakanyan, M.A.; Mirzoyan, A.L.

    1989-01-01

    The problem is posed of predicting the number n k (t) of flare stars that have exhibited precisely k flares by the time t on the basis of data on these quantities known during the total time T of observations of the aggregate. The problem posed by Ambartsumyan of determining the distribution function f(ν) of the true frequency of stellar flares from known chronology of these data is equivalent to the limiting form of their formulation - prediction in the future over an infinitely long time. An exact analytic solution of the problem obtained without any assumption about the function f(ν) is given. It permits prediction of the steady flare activity of the aggregate into both the future and the (known) past. It follows from this solution that prediction into the future is in principle impossible to times that exceed the doubled time 2T of the available observations (this means that the problem of determining of the function f(ν) cannot be solved). Moreover, because of the unavoidable fluctuations in the observational data n k (T), such prediction is limited to even shorter times, and these are shorter the larger the value of k. Prediction into the past and into the future on the basis of the data n k (T) at the present time and its possible errors due to small fluctuations in these data are illustrated for the examples of the Pleiades and the Orion aggregate

  1. Improving the technology of purification of gas emissions petrochemical industries

    OpenAIRE

    USMANOVA R.R.; ZAIKOV G.E.

    2014-01-01

    The technology of cleaning of gas emissions flares in the production of synthetic rubber. Developed dynamic scrubber for scrubbing gas emissions. Complex studies served as the basis for the design of an air purification system of industrial premises. Purification of gas emissions before combustion in flares has significantly reduced air pollution by toxic substances.

  2. Diagnostics of electron-heated solar flare models. III - Effects of tapered loop geometry and preheating

    Science.gov (United States)

    Emslie, A. G.; Li, Peng; Mariska, John T.

    1992-01-01

    A series of hydrodynamic numerical simulations of nonthermal electron-heated solar flare atmospheres and their corresponding soft X-ray Ca XIX emission-line profiles, under the conditions of tapered flare loop geometry and/or a preheated atmosphere, is presented. The degree of tapering is parameterized by the magnetic mirror ratio, while the preheated atmosphere is parameterized by the initial upper chromospheric pressure. In a tapered flare loop, it is found that the upward motion of evaporated material is faster compared with the case where the flare loop is uniform. This is due to the diverging nozzle seen by the upflowing material. In the case where the flare atmosphere is preheated and the flare geometry is uniform, the response of the atmosphere to the electron collisional heating is slow. The upward velocity of the hydrodynamic gas is reduced due not only to the large coronal column depth, but also to the increased inertia of the overlying material. It is concluded that the only possible electron-heated scenario in which the predicted Ca XIX line profiles agree with the BCS observations is when the impulsive flare starts in a preheated dense corona.

  3. Differences of serum procalcitonin levels between bacterial infection and flare in systemic lupus erythematosus patients

    Science.gov (United States)

    Patrick, J.; Marpaung, B.; Ginting, Y.

    2018-03-01

    Differentiate bacterial infections from flare in SLE patients is difficult to do because clinical symptoms of infection is similar to flare. SLE patients with infection require antibiotic therapy with decreased doses of immunosuppressant while in flare diseases require increased immunosuppressant. Procalcitonin (PCT), a biological marker, increased in serum patients with bacterial infections and expected to be a solution of problem. The aim of this study was to examine the function of PCT serum as marker to differentiate bacterial infection and flare in SLE patients. This cross-sectional study was conducted in Adam Malik Hospital from January-July 2017. We examined 80 patients SLE flare (MEX-SLEDAI>5), screen PCT and culture according to focal infection. Data were statistically analyzed. 80 SLE patients divided into 2 groups: bacterial infection group (31 patients) and non-infection/flare group (49 patients). Median PCT levels of bacterial infection group was 1.66 (0.04-8.45)ng/ml while flare group was 0.12 (0.02-0.81)ng/ml. There was significant difference of serum Procalcitonin level between bacterial infection and flare group in SLE patients (p=0.001). Procalcitonin serum levels can be used as a biomarker to differentiate bacterial infections and flare in SLE patients.

  4. Solar Flares and Their Prediction

    Science.gov (United States)

    Adams, Mitzi L.

    1999-01-01

    Solar flares and coronal mass ejection's (CMES) can strongly affect the local environment at the Earth. A major challenge for solar physics is to understand the physical mechanisms responsible for the onset of solar flares. Flares, characterized by a sudden release of energy (approx. 10(exp 32) ergs for the largest events) within the solar atmosphere, result in the acceleration of electrons, protons, and heavier ions as well as the production of electromagnetic radiation from hard X-rays to km radio waves (wavelengths approx. = 10(exp -9) cm to 10(exp 6) cm). Observations suggest that solar flares and sunspots are strongly linked. For example, a study of data from 1956-1969, reveals that approx. 93 percent of major flares originate in active regions with spots. Furthermore, the global structure of the sunspot magnetic field can be correlated with flare activity. This talk will review what we know about flare causes and effects and will discuss techniques for quantifying parameters, which may lead to a prediction of solar flares.

  5. How flares can be understood

    International Nuclear Information System (INIS)

    Severny, A.B.

    1977-01-01

    Specific features of the flare phenomenon which are important for understanding of flares are the following: (1) Fine structure of visible emission of flares, especially at the very beginning and in the pre-flare active region. This structure can be seen also in later stages of development as bright points, some of which exist from the flare beginning (Babin's observations at Crimea, 1972-1976). (2) Turbulent motion with velocities up to 250-300 km s -1 as can be estimated from broadening of emission lines. (3) Predominantly red asymmetry of emission lines in the explosive phase and during further development of flares. (4) 'Supersonic' velocities and supergravitational accelerations of separate moving masses of the flare plasma. (5) The appearance of flares in areas with high grad H, exceeding 0.1 G km -1 which is equivalent to regions of electric currents > approximately 10 11 A. (6) Strong variations of net magnetic flux through the active region, as it follows from Meudon, Crimean, and Sacramento Peak (Rust's) observations. (Auth.)

  6. Estimating soot emissions from an elevated flare

    Science.gov (United States)

    Almanza, Victor; Sosa, Gustavo

    2009-11-01

    Combustion aerosols are one of the major concerns in flaring operations, due to both health and environmental hazards. Preliminary results are presented for a 2D transient simulation of soot formation in a reacting jet with exit velocity of 130 m/s under a 5 m/s crossflow released from a 50 m high elevated flare and a 50 cm nozzle. Combustion dynamics was simulated with OpenFOAM. Gas-phase non-premixed combustion was modeled with the Chalmers PaSR approach and a κ-ɛ turbulence model. For soot formation, Moss model was used and the ISAT algorithm for solving the chemistry. Sulfur chemistry was considered to account for the sourness of the fuel. Gas composition is 10 % H2S and 90 % C2H4. A simplified Glassman reaction mechanism was used for this purpose. Results show that soot levels are sensitive to the sulfur present in the fuel, since it was observed a slight decrease in the soot volume fraction. NSC is the current oxidation model for soot formation. Predicted temperature is high (about 2390 K), perhaps due to soot-radiation interaction is not considered yet, but a radiation model implementation is on progress, as well as an oxidation mechanism that accounts for OH radical. Flame length is about 50 m.

  7. Analysis of the effect of dissimilar welding in a high pressure flare stack

    International Nuclear Information System (INIS)

    Mahdi Ezwan Mahmoud; Mohd Harun; Zaifol Samsu; Norasiah Kasim; Zaiton Selamat; Alahuddin, K.H.

    2010-01-01

    A flare stack is an elevated vertical stack found in a natural gas processing plant, used primarily for combusting waste gases released by pressure relief valves. The materials used for our high pressure flare tip are carbon steel (CS) type A516 Gr. 55 for its lower portion, and stainless steel (SS) 310 for its upper portion. Both were combined into a single unit by arc welding (dissimilar welding), with SS310 as a base metal. After 5 years of operations, few mechanical deformations were observed on the flare stack, along with corrosion deposit on the CS portion of the flare. Detailed analysis shows the presence of toe and shrinkage cracks, along with spheroidization of pearlite in the CS. These are caused by factors such as mismatched welding and coefficient of thermal expansion (CTE) between the metals. These factors helped exacerbate crack initiation and propagation. Based on the evidence collected, it is recommended that the CS A516 be replaced with SS310. (author)

  8. Solar neighbourhood flare stars - a review

    International Nuclear Information System (INIS)

    Kunkel, W.E.

    1975-01-01

    The review concentrates on 'astronomical' aspects of flare activity, such as where, and under what circumstances flare activity is found in the solar vicinity. Non-classical activity is briefly described (without regard for completeness) and the influence of detection effects on flare observations is treated. Flare stars discovered during the last four years are described and flare activity of local dMe stars is compared. The BY Draconis syndrome is discussed followed by some remarks about rotation. Pleiades flare activity is compared to that of the solar neighbourhood and evidence for the evolution of flare activity in stars is examined. (Auth.)

  9. Flare colours and luminosities

    International Nuclear Information System (INIS)

    Cristaldi, S.; Rodono, M.

    1975-01-01

    Flare colours determined from simultaneous UBV observations made at Catania Observatory and from sequential UBV observations made at McDonald Observatory are presented. They fit fairly well with the theoretical colours computed according to the Gurzadian's (1970) non-thermal model. Only part of the observed flare colours are consistent with the solar type models by Gershberg (1967) and Kunkel (1970). From a B-band patrol of UV Cet-type stars carried out from 1967 to 1972, some quantitative estimates of flare frequencies and luminosities and their average contributions to the stellar radiation are given. The corresponding parameters for the Sun, which were estimated from 'white light' flare activity, are also given for comparison. The Sun and V 1216 Sgr can be regarded as low-activity flare stars of the type found by Kunkel (1973). (Auth.)

  10. Flares on a Bp Star

    Science.gov (United States)

    Mullan, D. J.

    2009-09-01

    Two large X-ray flares have been reported from the direction of a magnetic B2p star (σ Ori E). Sanz-Forcada et al. have suggested that the flares did not occur on the B2p star but on a companion of late spectral type. A star which is a candidate for a late-type flare star near σ Ori E has recently been identified by Bouy et al. However, based on the properties of the flares, and based on a recent model of rotating magnetospheres, we argue that, rather than attributing the two flares to a late-type dwarf, it is a viable hypothesis that the flares were magnetic phenomena associated with the rotating magnetosphere of the B2p star itself.

  11. FLARES ON A Bp STAR

    International Nuclear Information System (INIS)

    Mullan, D. J.

    2009-01-01

    Two large X-ray flares have been reported from the direction of a magnetic B2p star (σ Ori E). Sanz-Forcada et al. have suggested that the flares did not occur on the B2p star but on a companion of late spectral type. A star which is a candidate for a late-type flare star near σ Ori E has recently been identified by Bouy et al. However, based on the properties of the flares, and based on a recent model of rotating magnetospheres, we argue that, rather than attributing the two flares to a late-type dwarf, it is a viable hypothesis that the flares were magnetic phenomena associated with the rotating magnetosphere of the B2p star itself.

  12. Search for relation between flares and photometric variability outside of flares in EV Lac

    International Nuclear Information System (INIS)

    Rojzman, G.Sh.

    1984-01-01

    The observations of the flare star EV Lac in July-September 1981 have confirmed the existence of photometric variability outside the flares during the night. It was found that, as a rule, a slow increase of brightness in U and B bands during 1-2 hours preceded the flares. It is suggested that the variability outside the flares is the result of the variability of chpomospheric emission lines and continuum that are emitted by the chromospheric preflare formations

  13. Proton solar flares

    International Nuclear Information System (INIS)

    Shaposhnikova, E.F.

    1979-01-01

    The observations of proton solar flares have been carried out in 1950-1958 using the extrablackout coronograph of the Crimea astrophysical observatory. The experiments permit to determine two characteristic features of flares: the directed motion of plasma injection flux from the solar depths and the appearance of a shock wave moving from the place of the injection along the solar surface. The appearance of the shock wave is accompanied by some phenomena occuring both in the sunspot zone and out of it. The consistent flash of proton flares in the other groups of spots, the disappearance of fibres and the appearance of eruptive prominences is accomplished in the sunspot zone. Beyond the sunspot zone the flares occur above spots, the fibres disintegrate partially or completely and the eruptive prominences appear in the regions close to the pole

  14. Periodic Accretion-powered Flares from Colliding EMRIs as TDE Imposters

    Science.gov (United States)

    Metzger, Brian D.; Stone, Nicholas C.

    2017-07-01

    When a main-sequence star undergoes Roche lobe overflow onto a supermassive black hole (SMBH) in a circular extreme mass ratio inspiral (EMRI), a phase of steady mass transfer ensues. Over millions of years, the binary evolves to a period minimum before reversing course and migrating outward as a brown dwarf. Because the time interval between consecutive EMRIs is comparable to the mass-transfer timescale, the semimajor axes of two consecutive mass-transferring EMRIs will cross on a radial scale of less than a few au. We show that such EMRI crossing events are inevitably accompanied by a series of mildly relativistic, grazing physical collisions between the stars. Each collision strips a small quantity of mass, primarily from the more massive star, which generally increases their radial separation to set up the next collision after a delay of decades to centuries (or longer) set by further gravitational radiation. Depending on the mass of the SMBH, this interaction can result in {N}{{c}}˜ 1{--}{10}4 gas production events of mass ˜ {M}⊙ /{N}{{c}}, thus powering a quasi-periodic sequence of SMBH accretion-powered flares over a total duration of thousands of years or longer. Although the EMRI rate is 2-3 orders of magnitude lower than the rate of tidal disruption events (TDEs), the ability of a single interacting EMRI pair to produce a large number of luminous flares—and to make more judicious use of the available stellar fuel—could make their observed rate competitive with the TDE rate, enabling them to masquerade as “TDE imposters.” Gas produced by EMRI collisions is easier to circularize than the highly eccentric debris streams produced in TDEs. We predict flares with bolometric luminosities that decay both as power laws shallower than {t}-5/3 and as decaying exponentials in time. Viscous spreading of the gaseous disks produced by the accumulation of previous mass-stripping events will place a substantial mass of gas on radial scales ≳ 10{--}100 {au

  15. Stability and special solutions to the conducting dusty gas model

    International Nuclear Information System (INIS)

    Calmelet, C.J.

    1987-01-01

    Models of the flow of a dusty, conducting and non-conducting gas are examined. Exact solutions for a conducting dusty gas model in the presence of a magnetic field are developed for two different flow domains. The exact solutions are calculated in the cases of negligible and non-negligible induced magnetic field. Stability theorems are developed which depend on the flow parameters of the dusty gas and the magnetic field. In particular, a universal stability theorem is obtained when the dusty gas flow is electrically conducting in the presence of an applied magnetic field, and the dust particles are non-uniformly distributed

  16. Transient behavior of flare-associated solar wind. II - Gas dynamics in a nonradial open field region

    Science.gov (United States)

    Nagai, F.

    1984-01-01

    Transient behavior of flare-associated solar wind in the nonradial open field region is numerically investigated, taking into account the thermal and dynamical coupling between the chromosphere and the corona. A realistic steady solar wind is constructed which passes through the inner X-type critical point in the rapidly diverging region. The wind speed shows a local maximum at the middle, O-type, critical point. The wind's density and pressure distributions decrease abruptly in the rapidly diverging region of the flow tube. The transient behavior of the wind following flare energy deposition includes ascending and descending conduction fronts. Thermal instability occurs in the lower corona, and ascending material flows out through the throat after the flare energy input ceases. A local density distribution peak is generated at the shock front due to the pressure deficit just behind the shock front.

  17. Transient magnetic field changes in flares

    International Nuclear Information System (INIS)

    Patterson, A.; Zirin, H.

    1981-01-01

    Magnetic changes have been detected with the videomagnetograph (VMG) at Big Bear during two large flares on 1979 November 5. Two kinds of changes were detected in both flares: a decrease in satellite field strength near the locus of the flare and the appearance of strong transient fields during the peak of the flare. We explain why we believe that the observed effects are real and not instrumental and discuss their significance for flare studies

  18. Radio imaging of solar flares using the very large array - New insights into flare process

    Science.gov (United States)

    Kundu, M. R.; Schmahl, E. J.; Vlahos, L.; Velusamy, T.

    1982-01-01

    An interpretation of VLA observations of microwave bursts is presented in an attempt to distinguish between certain models of flares. The VLA observations provide information about the pre-flare magnetic field topology and the existence of mildly relativistic electrons accelerated during flares. Examples are shown of changes in magnetic field topology in the hour before flares. In one case, new bipolar loops appear to emerge, which is an essential component of the model developed by Heyvaerts et al. (1977). In another case, a quadrupole structure, suggestive of two juxtaposed bipolar loops, appears to trigger the flare. Because of the observed diversity of magnetic field topologies in microwave bursts, it is believed that the magnetic energy must be dissipated in more than one way. The VLA observations are clearly providing means for sorting out the diverse flare models.

  19. Modelling blazar flaring using a time-dependent fluid jet emission model - an explanation for orphan flares and radio lags

    Science.gov (United States)

    Potter, William J.

    2018-01-01

    Blazar jets are renowned for their rapid violent variability and multiwavelength flares, however, the physical processes responsible for these flares are not well understood. In this paper, we develop a time-dependent inhomogeneous fluid jet emission model for blazars. We model optically thick radio flares for the first time and show that they are delayed with respect to the prompt optically thin emission by ∼months to decades, with a lag that increases with the jet power and observed wavelength. This lag is caused by a combination of the travel time of the flaring plasma to the optically thin radio emitting sections of the jet and the slow rise time of the radio flare. We predict two types of flares: symmetric flares - with the same rise and decay time, which occur for flares whose duration is shorter than both the radiative lifetime and the geometric path-length delay time-scale; extended flares - whose luminosity tracks the power of particle acceleration in the flare, which occur for flares with a duration longer than both the radiative lifetime and geometric delay. Our model naturally produces orphan X-ray and γ-ray flares. These are caused by flares that are only observable above the quiescent jet emission in a narrow band of frequencies. Our model is able to successfully fit to the observed multiwavelength flaring spectra and light curves of PKS1502+106 across all wavelengths, using a transient flaring front located within the broad-line region.

  20. Photospheric Magnetic Field Properties of Flaring versus Flare-quiet Active Regions. II. Discriminant Analysis

    Science.gov (United States)

    Leka, K. D.; Barnes, G.

    2003-10-01

    We apply statistical tests based on discriminant analysis to the wide range of photospheric magnetic parameters described in a companion paper by Leka & Barnes, with the goal of identifying those properties that are important for the production of energetic events such as solar flares. The photospheric vector magnetic field data from the University of Hawai'i Imaging Vector Magnetograph are well sampled both temporally and spatially, and we include here data covering 24 flare-event and flare-quiet epochs taken from seven active regions. The mean value and rate of change of each magnetic parameter are treated as separate variables, thus evaluating both the parameter's state and its evolution, to determine which properties are associated with flaring. Considering single variables first, Hotelling's T2-tests show small statistical differences between flare-producing and flare-quiet epochs. Even pairs of variables considered simultaneously, which do show a statistical difference for a number of properties, have high error rates, implying a large degree of overlap of the samples. To better distinguish between flare-producing and flare-quiet populations, larger numbers of variables are simultaneously considered; lower error rates result, but no unique combination of variables is clearly the best discriminator. The sample size is too small to directly compare the predictive power of large numbers of variables simultaneously. Instead, we rank all possible four-variable permutations based on Hotelling's T2-test and look for the most frequently appearing variables in the best permutations, with the interpretation that they are most likely to be associated with flaring. These variables include an increasing kurtosis of the twist parameter and a larger standard deviation of the twist parameter, but a smaller standard deviation of the distribution of the horizontal shear angle and a horizontal field that has a smaller standard deviation but a larger kurtosis. To support the

  1. What's an Asthma Flare-Up?

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Asthma Flare-Ups KidsHealth / For Parents / Asthma Flare-Ups ... español ¿Qué es una crisis asmática? What Are Asthma Flare-Ups? Keeping asthma under control helps kids ...

  2. Feature Selection, Flaring Size and Time-to-Flare Prediction Using Support Vector Regression, and Automated Prediction of Flaring Behavior Based on Spatio-Temporal Measures Using Hidden Markov Models

    Science.gov (United States)

    Al-Ghraibah, Amani

    Solar flares release stored magnetic energy in the form of radiation and can have significant detrimental effects on earth including damage to technological infrastructure. Recent work has considered methods to predict future flare activity on the basis of quantitative measures of the solar magnetic field. Accurate advanced warning of solar flare occurrence is an area of increasing concern and much research is ongoing in this area. Our previous work 111] utilized standard pattern recognition and classification techniques to determine (classify) whether a region is expected to flare within a predictive time window, using a Relevance Vector Machine (RVM) classification method. We extracted 38 features which describing the complexity of the photospheric magnetic field, the result classification metrics will provide the baseline against which we compare our new work. We find a true positive rate (TPR) of 0.8, true negative rate (TNR) of 0.7, and true skill score (TSS) of 0.49. This dissertation proposes three basic topics; the first topic is an extension to our previous work [111, where we consider a feature selection method to determine an appropriate feature subset with cross validation classification based on a histogram analysis of selected features. Classification using the top five features resulting from this analysis yield better classification accuracies across a large unbalanced dataset. In particular, the feature subsets provide better discrimination of the many regions that flare where we find a TPR of 0.85, a TNR of 0.65 sightly lower than our previous work, and a TSS of 0.5 which has an improvement comparing with our previous work. In the second topic, we study the prediction of solar flare size and time-to-flare using support vector regression (SVR). When we consider flaring regions only, we find an average error in estimating flare size of approximately half a GOES class. When we additionally consider non-flaring regions, we find an increased average

  3. Lagrangian solution of supersonic real gas flows

    International Nuclear Information System (INIS)

    Loh, Chingyuen; Liou, Mengsing

    1993-01-01

    This paper details the procedure of the real gas Riemann solution in the Lagrangian approach originally proposed by Loh and Hui for perfect gases. The extension to real gases is nontrivial and requires substantial development of an exact real-gas Riemann solver for the Lagrangian form of conservation laws. The first-order Gudonov scheme is enhanced for accuracy by adding limited anti-diffusive terms according to Sweby. Extensive calculations were made to test the accuracy and robustness of the present real gas Lagrangian approach, including complex wave interactions of different types. The accuracy for capturing 2D oblique waves and slip line is clearly demonstrated. In addition, we also show the real gas effect in a generic engine nozzle

  4. Influences of misprediction costs on solar flare prediction

    Science.gov (United States)

    Huang, Xin; Wang, HuaNing; Dai, XingHua

    2012-10-01

    The mispredictive costs of flaring and non-flaring samples are different for different applications of solar flare prediction. Hence, solar flare prediction is considered a cost sensitive problem. A cost sensitive solar flare prediction model is built by modifying the basic decision tree algorithm. Inconsistency rate with the exhaustive search strategy is used to determine the optimal combination of magnetic field parameters in an active region. These selected parameters are applied as the inputs of the solar flare prediction model. The performance of the cost sensitive solar flare prediction model is evaluated for the different thresholds of solar flares. It is found that more flaring samples are correctly predicted and more non-flaring samples are wrongly predicted with the increase of the cost for wrongly predicting flaring samples as non-flaring samples, and the larger cost of wrongly predicting flaring samples as non-flaring samples is required for the higher threshold of solar flares. This can be considered as the guide line for choosing proper cost to meet the requirements in different applications.

  5. Markets slow to develop for Niger delta gas reserves

    International Nuclear Information System (INIS)

    Thomas, D.

    1995-01-01

    Nigeria produces a very high quality, light, sweet crude oil but with a large percentage of associated gas derived from a high gas-to-oil ratio. Official proved gas reserves, both associated and nonassociated, are 120 tcf. Proved and probable reserves are estimated as high as 300 tcf. The internal market for gas has only begun to develop since the 1980s, and as a result approximately 77% of associated gas production is flared. Domestic gas consumption is currently approximately 700 MMcfd and is projected to have a medium term potential of 1.450 bcfd. The article discusses resource development, gas markets, gas flaring, gas use programs, the Bonny LNG scheme, the gas reserve base, LNG project status, competition, and energy opportunities

  6. Land based use of natural gas - distribution solutions

    International Nuclear Information System (INIS)

    Jordanger, Einar; Moelnvik, Mona J.; Owren, Geir; Einang, Per Magne; Grinden, Bjoern; Tangen, Grethe

    2002-05-01

    The report presents results from the project ''Landbasert bruk av naturgass - distribusjonsloesninger'' (Land based use of natural gas - distribution solutions). It describes the aims of the project, the political external conditions for the use of natural gas, some environmental profits by changing from petroleum and coal to natural gas, the Norwegian infrastructure, the optimisation of energy transport, strategic consequences of the introduction of LNG and the practical consequences of the Enova strategy

  7. Detection of a gas flaring signature in the AERONET optical properties of aerosols at a tropical station in West Africa

    Science.gov (United States)

    Fawole, Olusegun G.; Cai, Xiaoming; Levine, James G.; Pinker, Rachel T.; MacKenzie, A. R.

    2016-12-01

    The West African region, with its peculiar climate and atmospheric dynamics, is a prominent source of aerosols. Reliable and long-term in situ measurements of aerosol properties are not readily available across the region. In this study, Version 2 Level 1.5 Aerosol Robotic Network (AERONET) data were used to study the absorption and size distribution properties of aerosols from dominant sources identified by trajectory analysis. The trajectory analysis was used to define four sources of aerosols over a 10 year period. Sorting the AERONET aerosol retrievals by these putative sources, the hypothesis that there exists an optically distinct gas flaring signal was tested. Dominance of each source cluster varies with season: desert-dust (DD) and biomass burning (BB) aerosols are dominant in months prior to the West African Monsoon (WAM); urban (UB) and gas flaring (GF) aerosol are dominant during the WAM months. BB aerosol, with single scattering albedo (SSA) at 675 nm value of 0.86 ± 0.03 and GF aerosol with SSA (675 nm) value of 0.9 ± 0.07, is the most absorbing of the aerosol categories. The range of Absorption Angstr&öm Exponent (AAE) for DD, BB, UB and GF classes are 1.99 ± 0.35, 1.45 ± 0.26, 1.21 ± 0.38 and 0.98 ± 0.25, respectively, indicating different aerosol composition for each source. The AAE (440-870 nm) and Angstr&öm Exponent (AE) (440-870 nm) relationships further show the spread and overlap of the variation of these optical and microphysical properties, presumably due in part to similarity in the sources of aerosols and in part, due to mixing of air parcels from different sources en route to the measurement site.

  8. Impact of solution gas on SAGD performance

    Energy Technology Data Exchange (ETDEWEB)

    Das, Swapan K. [Marathon Oil Corporation (United States)

    2011-07-01

    In the Athabasca region of Canada, steam assisted gravity drainage (SAGD) is used as a means to enhance oil recovery in the highly viscous oil reservoirs. During steam injection, the solution gas evolves from oil phase as a non-condensable gas. Researchers assessed through simulations that non-condensable gas has a significant negative effect on SAGD performance although field operations might show a less severe effect. This research aimed at finding the reason for the difference between simulation and field results. Simulations were conducted in homogeneous and heterogeneous models with properties from a typical Athabasca reservoir. Results showed that the solubility of gas in the liquids has to be correctly taken into account, otherwise simulation models will overestimate the gas accumulation. This paper looked into the behavior of methane gas in simulation and field operations and highlighted the reasons for the discrepancies between their results.

  9. Flare observation by the satellite 'Hinotori'

    International Nuclear Information System (INIS)

    Tanaka, Toshio

    1981-01-01

    The satellite ''Hinotori'' makes 5 rounds a day and is doing flare observation. The total observation days amounted to 94 days. Among the observed flares, the quiet mode flares were picked up from the reproduced data. The plot of the time variation of flares was obtained for four energy bands, HXM-1 (17 to 40 keV), HXM2 - 7 (over 40 keV), FLM-L (1 to 5 keV) and FLM-H (5 to 12 keV). At present, the judge of flares is made by using hard X-ray of the HXM-1 plot. False signals were completely removed. A large percentage of big flares was collected by Hinotori, eleven X-class flares were recorded. The operation status of ''Hinotori'' has been in good condition. The spin frequency has increased with a constant rate. (Kato, T.)

  10. Offshore production flares: a PETROBRAS review

    Energy Technology Data Exchange (ETDEWEB)

    Pagot, Paulo R.; Burmann, Clovis P.; Araujo, Paulo Bento de; Motomura, Tsukasa [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The purpose of the present work is to briefly present the offshore flare system technological evolution and the main design criteria for flare and its supporting structure. In order to perform the aimed task, this work was divided into two parts: the first part presents the technological evolution of the offshore production flares and the second one discusses the flare system designing criteria. The evolution of the technology associated to the offshore production flares is organized by the authors just dividing the history in four chronological phases. Each phase is defined by the predominant use of the, by the time, most up-to-date technological alternative and it will be described with the help of sketches, drawings, photographs, data and information about the platforms where such technologies were applied. The second part of the present work discusses the dimensional criteria, interesting aspects and flaws of the offshore flare systems in two different fields, which are: definition of the flare system capacity; and flow and thermal design of the flare system. (author)

  11. Fast electrons in small solar flares

    International Nuclear Information System (INIS)

    Lin, R.P.

    1975-01-01

    Because approximately 5-100 keV electrons are frequently accelerated and emitted by the Sun in small flares, it is possible to define a detailed characteristic physical picture of these events. The review summarizes both the direct spacecraft observations of non-relativistic solar electrons, and observations of the X-ray and radio emission generated by these particles at the Sun and in the interplanetary medium. These observations bear on the basic astrophysical process of particle acceleration in tenuous plasmas. It is found that in many small solar flares the approximately 5-100 keV electrons accelerated during flash phase constitute the bulk of the total flare energy. Thus the basic flare mechanism in these flares essentially converts the available flare energy into fast electrons. These electrons may produce the other flare electromagnetic emissions through their interactions with the solar atmosphere. In large proton flares these electrons may provide the energy to eject material from the Sun and to create a shock wave which could then accelerate nuclei and electrons to much higher energies. (Auth.)

  12. Parameterization of solar flare dose

    International Nuclear Information System (INIS)

    Lamarche, A.H.; Poston, J.W.

    1996-01-01

    A critical aspect of missions to the moon or Mars will be the safety and health of the crew. Radiation in space is a hazard for astronauts, especially high-energy radiation following certain types of solar flares. A solar flare event can be very dangerous if astronauts are not adequately shielded because flares can deliver a very high dose in a short period of time. The goal of this research was to parameterize solar flare dose as a function of time to see if it was possible to predict solar flare occurrence, thus providing a warning time. This would allow astronauts to take corrective action and avoid receiving a dose greater than the recommended limit set by the National Council on Radiation Protection and Measurements (NCRP)

  13. Dispersion and exposure of sour gas flare emissions

    International Nuclear Information System (INIS)

    Davies, M.

    2002-01-01

    This presentation described the implications of flare research project findings with reference to reduced combustion efficiency, stack plume down wash and minor species. A plume model shows that reduced combustion efficiency decreases the energy available for plume rise. Reduced combustion may therefore decrease H 2 S to SO 2 conversion. Stack plume down wash can decrease plume rise under high wind speed conditions, and in extreme cases can also preclude any plume rise. Minor species include vapour phase emissions of polynuclear aromatic hydrocarbons (PAH), benzene, toluene, ethyl-benzene and xylenes (BTEX), and aldehydes. They also include particulate phase emissions such as soot and PAH. Observed concentrations of minor species were presented along with predicted vapour phase concentrations and particulate phase emissions. The standard modelling approaches used in this study included the Gaussian plume model, flame height, plume rise and dispersion. figs

  14. Radon Concentration in Outdoors and Indoors Around the Flare in Oil Mine Sites; Konsentrasi Gas Radon di Udara di Luar dan Dalam Rumah Sekitar Nyala-api Kawasan Tambang Minyak

    Energy Technology Data Exchange (ETDEWEB)

    Sutarman,; Wahyudi, [Centre for Research and Development of Radiation Safety and Nuclear Biomedicine, National Nuclear Energy Agency, Jakarta (Indonesia); Luhantara, [University of Indonesia, Jakarta (Indonesia)

    2003-03-15

    The flares are much found at the oil exploration areas which appear the combustion gases emission to the environment that pass through a pipe at about 8 m high from the ground level. The flare is released into the environment together with the hydrocarbon and radon gases. This study has been carried out the measurement of the radon gas concentration only. Radon is a radioactive gas which comes from the natural radioactive decay of uranium ({sup 238}U). The outdoor radon concentrations were measured in 23 locations with the two-filter method. The locations were determined by a circle which the flare as the point center. The outdoor radon concentrations were measured in 74 houses (more than distance of 600 m from the flare) with the alpha track detector (CR-39) placed in the living rooms for about three months. The measurements of the radon concentrations were carried out in Cepu, Cirebon, and Prabumulih oil mine sites. The results showed that the outdoor radon concentrations a range of 108 Bq/m{sup 3} to 256 Bq/m{sup 3} in Cepu, 248 Bq/m{sup 3} to 3525 Bq/m{sup 3} in Cirebon, and 51 Bq/m{sup 3} to 114 Bq/m{sup 3} in Prabumulih. The results showed that the indoor radon concentrations a range of 11 Bq/m{sup 3} to 38 Bq/m{sup 3} in Cepu, 28 Bq/m{sup 3} to 184 Bq/m{sup 3} in Cirebon, and 12 Bq/m{sup 3} to 38 Bq/m{sup 3} in Prabumulih. The data of the maximum radon concentration in outdoor air was higher than an actual level which recommended by International Atomic Energy Agency (IAEA) for workplaces. The maximum radon concentration in indoor air was lower than an actual level which recommended by IAEA for dwellings. IAEA recommends the actual level of 1000 Bq/m{sup 3} for workplaces and 200 Bq/m{sup 3} for dwellings. These data will be used for the baseline data of the environmental radioactivity in Indonesia. (author)

  15. Flare parameters inferred from a 3D loop model data base

    Science.gov (United States)

    Cuambe, Valente A.; Costa, J. E. R.; Simões, P. J. A.

    2018-06-01

    We developed a data base of pre-calculated flare images and spectra exploring a set of parameters which describe the physical characteristics of coronal loops and accelerated electron distribution. Due to the large number of parameters involved in describing the geometry and the flaring atmosphere in the model used, we built a large data base of models (˜250 000) to facilitate the flare analysis. The geometry and characteristics of non-thermal electrons are defined on a discrete grid with spatial resolution greater than 4 arcsec. The data base was constructed based on general properties of known solar flares and convolved with instrumental resolution to replicate the observations from the Nobeyama radio polarimeter spectra and Nobeyama radioheliograph (NoRH) brightness maps. Observed spectra and brightness distribution maps are easily compared with the modelled spectra and images in the data base, indicating a possible range of solutions. The parameter search efficiency in this finite data base is discussed. 8 out of 10 parameters analysed for 1000 simulated flare searches were recovered with a relative error of less than 20 per cent on average. In addition, from the analysis of the observed correlation between NoRH flare sizes and intensities at 17 GHz, some statistical properties were derived. From these statistics, the energy spectral index was found to be δ ˜ 3, with non-thermal electron densities showing a peak distribution ⪅107 cm-3, and Bphotosphere ⪆ 2000 G. Some bias for larger loops with heights as great as ˜2.6 × 109 cm, and looptop events were noted. An excellent match of the spectrum and the brightness distribution at 17 and 34 GHz of the 2002 May 31 flare is presented as well.

  16. SLIPPING MAGNETIC RECONNECTIONS WITH MULTIPLE FLARE RIBBONS DURING AN X-CLASS SOLAR FLARE

    International Nuclear Information System (INIS)

    Zheng, Ruisheng; Chen, Yao; Wang, Bing

    2016-01-01

    With the observations of the Solar Dynamics Observatory , we present the slipping magnetic reconnections with multiple flare ribbons (FRs) during an X1.2 eruptive flare on 2014 January 7. A center negative polarity was surrounded by several positive ones, and three FRs appeared. The three FRs showed apparent slipping motions, and hook structures formed at their ends. Due to the moving footpoints of the erupting structures, one tight semi-circular hook disappeared after the slippage along its inner and outer edges, and coronal dimmings formed within the hook. The east hook also faded as a result of the magnetic reconnection between the arcades of a remote filament and a hot loop that was impulsively heated by the under flare loops. Our results are accordant with the slipping magnetic reconnection regime in three-dimensional standard model for eruptive flares. We suggest that the complex structures of the flare are likely a consequence of the more complex flux distribution in the photosphere, and the eruption involves at least two magnetic reconnections.

  17. Solar flares through electric current interaction

    International Nuclear Information System (INIS)

    De Jager, C.

    1988-01-01

    The fundamental hypothesis by Alfven and Carlqvist (1967) that solar flares are related to electrical currents in the solar chromosphere and low corona is investigated in the light of modern observations. The authors confirm the important role of currents in solar flares. There must be tens of such current loops (flux threads) in any flare, and this explains the hierarchy of bursts in flares. The authors summarize quantitative data on energies, numbers of particles involved and characteristic times. A special case is the high-energy flare: this one may originate in the same way as less energetic ones, but it occurs in regions with higher magnetic field strength. Because of the high particle energies involved their emission seats live only very briefly; hence the area of emission coincides virtually with the seat of the instability. These flares are therefore the best examples for studying the primary instability leading to the flare. Finally, the authors compare the merits of the original Alfven-Carlqvist idea (that flares originate by current interruption) with the one that they are due to interaction (reconnection) between two or more fluxthreads. The authors conclude that a final decision cannot yet by made, although the observed extremely short time constants of flare bursts seem to demand a reconnection-type instability rather than interruption of a circuit

  18. Assessment of the Incidence of Posttreatment Endodontic Flare-ups in Patients undergoing Single-sitting Root Canal Therapies: A Clinical Study.

    Science.gov (United States)

    Priyank, Harsh; Devi, T M Chaitra; Goel, Pallavi; Sahu, Nivedita; Nihalani, Shweta; Shandilya, Ashutosh

    2016-10-01

    Endodontic therapy is one of the commonly used procedures for treating the teeth affected by various pathologies. One of the major problems for endodontists despite the advancements in the root canal procedures is the posttreatment endodontic flare-ups. Much debate exists regarding the completion of endodontic therapy in a single sitting or multiple sittings. Hence, we assessed the incidence of endodontic flare-ups in patients undergoing single-sitting root canal therapies. The present study included 200 patients who underwent single-sitting endodontic therapy. Clinical details and conditions of each and every tooth of every patient were recorded before and after the completion of endodontic therapy. Irrigation during the root canal procedures was done by 2.5% NaOCl solution in most of the cases while others were irrigated with various combinations of ethylenediaminetetraacetic acid (EDTA) and cycloheximide (CHX) solutions. Follow-up records and readings of the patents were noted and were subjected to statistical analysis. Four groups were formed which divided the patients equally on the basis of their age. Out of 50 patients in the age group of 21 to 30 years, only 4 showed posttreatment endodontic flare-ups, while no endodontic flare-up was recorded in patients with age group of 31 to 50 years. Only two male and four females showed flare-ups postoperatively. A nonsignificant correlation was obtained when flare-up cases were compared on the basis of type of irrigation solution used during canal preparation. Single-sitting endodontic therapy appears to be a successful procedure with good prognosis and minimal posttreatment flare-up results, even in patients with periapical pathologies. Single-sitting root canal procedures can be successfully carried in patients with vital or nonvital pulp tissues and also in patients with periapical lesions.

  19. Dwarf Star Erupts in Giant Flare

    Science.gov (United States)

    2005-01-01

    This movie taken by NASA'S Galaxy Evolution Explorer shows one of the largest flares, or star eruptions, ever recorded at ultraviolet wavelengths. The star, called GJ 3685A, just happened to be in the Galaxy Evolution Explorer's field of view while the telescope was busy observing galaxies. As the movie demonstrates, the seemingly serene star suddenly exploded once, then even more intensely a second time, pouring out in total about one million times more energy than a typical flare from our Sun. The second blast of light constituted an increase in brightness by a factor of at least 10,000. Flares are huge explosions of energy stemming from a single location on a star's surface. They are caused by the brief destruction of a star's magnetic fields. Many types of stars experience them, though old, small, rapidly rotating 'red dwarfs' like GJ 3685A tend to flare more frequently and dramatically. These stars, called flare stars, can experience powerful eruptions as often as every few hours. Younger stars, in general, also erupt more often. One of the reasons astronomers study flare stars is to gain a better picture and history of flare events taking place on the Sun. A preliminary analysis of the GJ 3685A flare shows that the mechanisms underlying stellar eruptions may be more complex than previously believed. Evidence for the two most popular flare theories was found. Though this movie has been sped up (the actual flare lasted about 20 minutes), time-resolved data exist for each one-hundredth of a second. These observations were taken at 2 p.m. Pacific time, April 24, 2004. In the still image, the time sequence starts in the upper left panel, continues in the upper right, then moves to the lower left and ends in the lower right. The circular and linear features that appear below and to the right of GJ 3685A during the flare event are detector artifacts caused by the extreme brightness of the flare.

  20. Sun and solar flares

    Energy Technology Data Exchange (ETDEWEB)

    McKenna-Lawlor, S. (Saint Patrick' s Coll., Maynooth (Ireland))

    1982-07-01

    The subject is discussed under the headings: the sun's core (thermonuclear reactions, energy transfer from core through radiation zone, convection zone, photosphere, chromosphere and corona); the photosphere (convection, granulation, sunspots, magnetic fields, solar cycle, rotation of the sun); solar variability and paleoclimatic records (correlation of low solar activity with increased /sup 14/C production in atmosphere); the chromosphere and corona (turbulence, temperature, coronal streamers, energy transfer); solar flares (cosmic rays, aurorae, spectra, velocity of flares, prominences, mechanisms of flares); the solar wind.

  1. Flare Characteristics from X-ray Light Curves

    Science.gov (United States)

    Gryciuk, M.; Siarkowski, M.; Sylwester, J.; Gburek, S.; Podgorski, P.; Kepa, A.; Sylwester, B.; Mrozek, T.

    2017-06-01

    A new methodology is given to determine basic parameters of flares from their X-ray light curves. Algorithms are developed from the analysis of small X-ray flares occurring during the deep solar minimum of 2009, between Solar Cycles 23 and 24, observed by the Polish Solar Photometer in X-rays (SphinX) on the Complex Orbital Observations Near-Earth of Activity of the Sun-Photon (CORONAS- Photon) spacecraft. One is a semi-automatic flare detection procedure that gives start, peak, and end times for single ("elementary") flare events under the assumption that the light curve is a simple convolution of a Gaussian and exponential decay functions. More complex flares with multiple peaks can generally be described by a sum of such elementary flares. Flare time profiles in the two energy ranges of SphinX (1.16 - 1.51 keV, 1.51 - 15 keV) are used to derive temperature and emission measure as a function of time during each flare. The result is a comprehensive catalogue - the SphinX Flare Catalogue - which contains 1600 flares or flare-like events and is made available for general use. The methods described here can be applied to observations made by Geosynchronous Operational Environmental Satellites (GOES), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and other broad-band spectrometers.

  2. Statistical investigation of flare stars. III. Flare stars in the general galactic star field

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.; Ambaryan, V.V.; Garibdzhanyan, A.T.; Mirzoyan, A.L.

    1989-01-01

    Some questions relating to the existence of a large number of flare stars in the general star field of the Galaxy are discussed. It is shown that only a small proportion of them can be found by photographic observations, and the fraction of field flare stars among such stars found in the regions of star clusters and associations does not exceed 10%. The ratio of the numbers of flare stars of the foreground and the background for a particular system depends on its distance, reaching zero at a distance of about 500 pc. The spatial density of flare stars in the Pleiades is at least two orders of magnitude greater than in the general galactic field. A lower limit for the number of flare stars in the Galaxy is estimated at 4.2 ·10 9 , and the number of nonflare red dwarfs at 2.1·10 10 . There are grounds for believing that they were all formed in star clusters and associations

  3. Flare Seismology from SDO Observations

    Science.gov (United States)

    Lindsey, Charles; Martinez Oliveros, Juan Carlos; Hudson, Hugh

    2011-10-01

    Some flares release intense seismic transients into the solar interior. These transients are the sole instance we know of in which the Sun's corona exerts a conspicuous influence on the solar interior through flares. The desire to understand this phenomenon has led to ambitious efforts to model the mechanisms by which energy stored in coronal magnetic fields drives acoustic waves that penetrate deep into the Sun's interior. These mechanisms potentially involve the hydrodynamic response of the chromosphere to thick-target heating by high-energy particles, radiative exchange in the chromosphere and photosphere, and Lorentz-force transients to account for acoustic energies estimated up to at 5X10^27 erg and momenta of order 6X10^19 dyne sec. An understanding of these components of flare mechanics promises more than a powerful diagnostic for local helioseismology. It could give us fundamental new insight into flare mechanics themselves. The key is appropriate observations to match the models. Helioseismic observations have identified the compact sources of transient seismic emission at the foot points of flares. The Solar Dynamics Observatory is now giving us high quality continuum-brightness and Doppler observations of acoustically active flares from HMI concurrent with high-resolution EUV observations from AIA. Supported by HXR observations from RHESSI and a broad variety of other observational resources, the SDO promises a leading role in flare research in solar cycle 24.

  4. KEPLER FLARES. I. ACTIVE AND INACTIVE M DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, Suzanne L.; Davenport, James R. A.; Kowalski, Adam F.; Wisniewski, John P.; Deitrick, Russell; Hilton, Eric J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Hebb, Leslie, E-mail: slhawley@uw.edu [Department of Physics, Hobart and William Smith Colleges, 300 Pulteney Street, Geneva, NY 14456 (United States)

    2014-12-20

    We analyzed Kepler short-cadence M dwarf observations. Spectra from the Astrophysical Research Consortium 3.5 m telescope identify magnetically active (Hα in emission) stars. The active stars are of mid-M spectral type, have numerous flares, and have well-defined rotational modulation due to starspots. The inactive stars are of early M type, exhibit less starspot signature, and have fewer flares. A Kepler to U-band energy scaling allows comparison of the Kepler flare frequency distributions with previous ground-based data. M dwarfs span a large range of flare frequency and energy, blurring the distinction between active and inactive stars designated solely by the presence of Hα. We analyzed classical and complex (multiple peak) flares on GJ 1243, finding strong correlations between flare energy, amplitude, duration, and decay time, with only a weak dependence on rise time. Complex flares last longer and have higher energy at the same amplitude, and higher energy flares are more likely to be complex. A power law fits the energy distribution for flares with log E{sub K{sub p}}> 31 erg, but the predicted number of low-energy flares far exceeds the number observed, at energies where flares are still easily detectable, indicating that the power-law distribution may flatten at low energy. There is no correlation of flare occurrence or energy with starspot phase, the flare waiting time distribution is consistent with flares occurring randomly in time, and the energies of consecutive flares are uncorrelated. These observations support a scenario where many independent active regions on the stellar surface are contributing to the observed flare rate.

  5. KEPLER FLARES. I. ACTIVE AND INACTIVE M DWARFS

    International Nuclear Information System (INIS)

    Hawley, Suzanne L.; Davenport, James R. A.; Kowalski, Adam F.; Wisniewski, John P.; Deitrick, Russell; Hilton, Eric J.; Hebb, Leslie

    2014-01-01

    We analyzed Kepler short-cadence M dwarf observations. Spectra from the Astrophysical Research Consortium 3.5 m telescope identify magnetically active (Hα in emission) stars. The active stars are of mid-M spectral type, have numerous flares, and have well-defined rotational modulation due to starspots. The inactive stars are of early M type, exhibit less starspot signature, and have fewer flares. A Kepler to U-band energy scaling allows comparison of the Kepler flare frequency distributions with previous ground-based data. M dwarfs span a large range of flare frequency and energy, blurring the distinction between active and inactive stars designated solely by the presence of Hα. We analyzed classical and complex (multiple peak) flares on GJ 1243, finding strong correlations between flare energy, amplitude, duration, and decay time, with only a weak dependence on rise time. Complex flares last longer and have higher energy at the same amplitude, and higher energy flares are more likely to be complex. A power law fits the energy distribution for flares with log E K p > 31 erg, but the predicted number of low-energy flares far exceeds the number observed, at energies where flares are still easily detectable, indicating that the power-law distribution may flatten at low energy. There is no correlation of flare occurrence or energy with starspot phase, the flare waiting time distribution is consistent with flares occurring randomly in time, and the energies of consecutive flares are uncorrelated. These observations support a scenario where many independent active regions on the stellar surface are contributing to the observed flare rate

  6. Midtreatment flare-ups.

    Science.gov (United States)

    Harrington, G W; Natkin, E

    1992-04-01

    It should be apparent that the prompt and effective treatment of midtreatment flare-ups of all types is an essential and integral part of the overall endodontic treatment procedure. The expeditious management of these flare-ups will do much to enhance a positive attitude among patients toward endodontic treatment and to ensure the well-being and comfort of these patients.

  7. Safety implications of bridging the energy supply/demand gap in Nigeria through associated natural gas utilization

    International Nuclear Information System (INIS)

    Akeredolu, Funso A.; Sonibare, Jacob A.

    2007-01-01

    There exists a wide energy supply/demand gap in Nigeria. The local generation of electricity meets only 31% of the demand of 10000 MW. By contrast, only 39.6% of the total installed capacity for electricity generation is achieved, owing to aging infrastructure, etc. The energy demand/supply pattern and infrastructure critically reviewed thus suggested the need to increase the electricity generation capacity. Furthermore, Nigeria flares 77% of her associated natural gas. Apart from the environmental penalties that flaring represents, in monetary terms, over the 110 years' life of Nigeria's gas reserves, a conservative estimate of the cost of the gas so-flared was $330 billion (based on $20/barrel average price of crude). It was safely inferred that the way forward in meeting the country's energy demand should include a strong element of gas utilization. In previous publications by this group, it was established that while domestic cooking could reduce the flared gas by about 5.4%, a cohesive policy on associated gas use for electricity generation could eliminate gas flaring. For domestic utilization of the associated gas, burner design and safety concerns were identified as the key challenges to overcome. The paper reports the effectiveness of odorizers in leakage detection/ prevention by the local consumers. It also discusses the issue of prevention of gas explosions. The previous cases of gas accidents were reviewed. The safety approaches proffered in the paper identified the relevant areas of research for safe delivery and consumption of natural gas in Nigeria. (Author)

  8. 40 CFR 65.164 - Performance test and flare compliance determination notifications and reports.

    Science.gov (United States)

    2010-07-01

    ... determination notifications and reports. 65.164 Section 65.164 Protection of Environment ENVIRONMENTAL..., Control Devices, and Routing to a Fuel Gas System or a Process § 65.164 Performance test and flare... an initially scheduled performance test, there is a delay (due to operational problems, etc.) in...

  9. Can we explain atypical solar flares?

    Science.gov (United States)

    Dalmasse, K.; Chandra, R.; Schmieder, B.; Aulanier, G.

    2015-02-01

    Context. We used multiwavelength high-resolution data from ARIES, THEMIS, and SDO instruments to analyze a non-standard, C3.3 class flare produced within the active region NOAA 11589 on 2012 October 16. Magnetic flux emergence and cancellation were continuously detected within the active region, the latter leading to the formation of two filaments. Aims: Our aim is to identify the origins of the flare taking the complex dynamics of its close surroundings into account. Methods: We analyzed the magnetic topology of the active region using a linear force-free field extrapolation to derive its 3D magnetic configuration and the location of quasi-separatrix layers (QSLs), which are preferred sites for flaring activity. Because the active region's magnetic field was nonlinear force-free, we completed a parametric study using different linear force-free field extrapolations to demonstrate the robustness of the derived QSLs. Results: The topological analysis shows that the active region presented a complex magnetic configuration comprising several QSLs. The considered data set suggests that an emerging flux episode played a key role in triggering the flare. The emerging flux probably activated the complex system of QSLs, leading to multiple coronal magnetic reconnections within the QSLs. This scenario accounts for the observed signatures: the two extended flare ribbons developed at locations matched by the photospheric footprints of the QSLs and were accompanied with flare loops that formed above the two filaments, which played no important role in the flare dynamics. Conclusions: This is a typical example of a complex flare that can a priori show standard flare signatures that are nevertheless impossible to interpret with any standard model of eruptive or confined flare. We find that a topological analysis, however, permitted us to unveil the development of such complex sets of flare signatures. Movies associated to Figs. 1, 3, and 9 are only available at the CDS via

  10. Active Longitude and Solar Flare Occurrences

    Science.gov (United States)

    Gyenge, N.; Ludmány, A.; Baranyi, T.

    2016-02-01

    The aim of the present work is to specify the spatio-temporal characteristics of flare activity observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Geostationary Operational Environmental Satellite (GOES) in connection with the behavior of the longitudinal domain of enhanced sunspot activity known as active longitude (AL). By using our method developed for this purpose, we identified the AL in every Carrington Rotation provided by the Debrecen Photoheliographic Data. The spatial probability of flare occurrence has been estimated depending on the longitudinal distance from AL in the northern and southern hemispheres separately. We have found that more than 60% of the RHESSI and GOES flares is located within +/- 36^\\circ from the AL. Hence, the most flare-productive active regions tend to be located in or close to the active longitudinal belt. This observed feature may allow for the prediction of the geo-effective position of the domain of enhanced flaring probability. Furthermore, we studied the temporal properties of flare occurrence near the AL and several significant fluctuations were found. More precisely, the results of the method are the following fluctuations: 0.8, 1.3, and 1.8 years. These temporal and spatial properties of the solar flare occurrence within the active longitudinal belts could provide us with an enhanced solar flare forecasting opportunity.

  11. Improving Students' Understanding of the Connections between the Concepts of Real-Gas Mixtures, Gas Ideal-Solutions, and Perfect-Gas Mixtures

    Science.gov (United States)

    Privat, Romain; Jaubert, Jean-Noël; Moine, Edouard

    2016-01-01

    In many textbooks of chemical-engineering thermodynamics, a gas mixture obeying the fundamental law pV[subscript m] = RT is most often called ideal-gas mixture (in some rare cases, the term perfect-gas mixture can be found). These textbooks also define the fundamental concept of ideal solution which in theory, can be applied indifferently to…

  12. Solubility of flue gas components in NaOH based scrubber solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sandelin, K; Backman, R

    1997-11-01

    The work reported here is a thermodynamic study on the solubility of flue gas components in aqueous solutions containing sodium salts. The result of the work is an equilibrium model. The model presented here includes sodium hydroxide and sodium salts that makes it possible to study simultaneous absorption of flue gas components in alkaline scrubber solutions. The model is applied on the absorption of a flue gas into a NaOH scrubber solution. The calculations show that it is possible to simultaneously absorb sulfur dioxide, sulfuric acid, and ammonia without carbon dioxide co-absorption. The calculations also show that gaseous NO and N{sub 2}O cannot be scrubbed unless they are oxidized to nitrate or reduced to ammonia. (author) SIHTI 2 Research Programme. 59 refs.

  13. Statistical Distributions of Optical Flares from Gamma-Ray Bursts

    International Nuclear Information System (INIS)

    Yi, Shuang-Xi; Yu, Hai; Wang, F. Y.; Dai, Zi-Gao

    2017-01-01

    We statistically study gamma-ray burst (GRB) optical flares from the Swift /UVOT catalog. We compile 119 optical flares, including 77 flares with redshift measurements. Some tight correlations among the timescales of optical flares are found. For example, the rise time is correlated with the decay time, and the duration time is correlated with the peak time of optical flares. These two tight correlations indicate that longer rise times are associated with longer decay times of optical flares and also suggest that broader optical flares peak at later times, which are consistent with the corresponding correlations of X-ray flares. We also study the frequency distributions of optical flare parameters, including the duration time, rise time, decay time, peak time, and waiting time. Similar power-law distributions for optical and X-ray flares are found. Our statistic results imply that GRB optical flares and X-ray flares may share the similar physical origin, and both of them are possibly related to central engine activities.

  14. Statistical Distributions of Optical Flares from Gamma-Ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Shuang-Xi [College of Physics and Engineering, Qufu Normal University, Qufu 273165 (China); Yu, Hai; Wang, F. Y.; Dai, Zi-Gao, E-mail: fayinwang@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2017-07-20

    We statistically study gamma-ray burst (GRB) optical flares from the Swift /UVOT catalog. We compile 119 optical flares, including 77 flares with redshift measurements. Some tight correlations among the timescales of optical flares are found. For example, the rise time is correlated with the decay time, and the duration time is correlated with the peak time of optical flares. These two tight correlations indicate that longer rise times are associated with longer decay times of optical flares and also suggest that broader optical flares peak at later times, which are consistent with the corresponding correlations of X-ray flares. We also study the frequency distributions of optical flare parameters, including the duration time, rise time, decay time, peak time, and waiting time. Similar power-law distributions for optical and X-ray flares are found. Our statistic results imply that GRB optical flares and X-ray flares may share the similar physical origin, and both of them are possibly related to central engine activities.

  15. FLARE RIBBON ENERGETICS IN THE EARLY PHASE OF AN SDO FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, L.; Hannah, I. G.; Hudson, H. S. [School of Physics and Astronomy, SUPA, University of Glasgow, Glasgow, G12 8QQ (United Kingdom); Innes, D. E. [Max Planck Institute for Solar System Research, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau (Germany)

    2013-07-10

    The sites of chromospheric excitation during solar flares are marked by extended extreme ultraviolet ribbons and hard X-ray (HXR) footpoints. The standard interpretation is that these are the result of heating and bremsstrahlung emission from non-thermal electrons precipitating from the corona. We examine this picture using multi-wavelength observations of the early phase of an M-class flare SOL2010-08-07T18:24. We aim to determine the properties of the heated plasma in the flare ribbons, and to understand the partition of the power input into radiative and conductive losses. Using GOES, SDO/EVE, SDO/AIA, and RHESSI, we measure the temperature, emission measure (EM), and differential emission measure of the flare ribbons, and deduce approximate density values. The non-thermal EM, and the collisional thick target energy input to the ribbons are obtained from RHESSI using standard methods. We deduce the existence of a substantial amount of plasma at 10 MK in the flare ribbons, during the pre-impulsive and early-impulsive phase of the flare. The average column EM of this hot component is a few times 10{sup 28} cm{sup -5}, and we can calculate that its predicted conductive losses dominate its measured radiative losses. If the power input to the hot ribbon plasma is due to collisional energy deposition by an electron beam from the corona then a low-energy cutoff of {approx}5 keV is necessary to balance the conductive losses, implying a very large electron energy content. Independent of the standard collisional thick-target electron beam interpretation, the observed non-thermal X-rays can be provided if one electron in 10{sup 3}-10{sup 4} in the 10 MK (1 keV) ribbon plasma has an energy above 10 keV. We speculate that this could arise if a non-thermal tail is generated in the ribbon plasma which is being heated by other means, for example, by waves or turbulence.

  16. FLARES AND THEIR UNDERLYING MAGNETIC COMPLEXITY

    International Nuclear Information System (INIS)

    Engell, Alexander J.; Golub, Leon; Korreck, Kelly; Siarkowski, Marek; Gryciuk, Magda; Sylwester, Janusz; Sylwester, Barbara; Cirtain, Jonathan

    2011-01-01

    SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like/transient events with active region (AR) 11024 being the only AR on disk. The Hinode X-Ray Telescope (XRT) and Solar Optical Telescope observe 67 of these events and identified their location from 12:00 UT on July 3 through 24:00 UT 2009 July 7. We find that the predominant mechanisms for flares observed by XRT are (1) flux cancellation and (2) the shearing of underlying magnetic elements. Point- and cusp-like flare morphologies seen by XRT all occur in a magnetic environment where one polarity is impeded by the opposite polarity and vice versa, forcing the flux cancellation process. The shearing is either caused by flux emergence at the center of the AR and separation of polarities along a neutral line or by individual magnetic elements having a rotational motion. Both mechanisms are observed to contribute to single- and multiple-loop flares. We observe that most loop flares occur along a large portion of a polarity inversion line. Point- and cusp-like flares become more infrequent as the AR becomes organized with separation of the positive and negative polarities. SphinX, which allows us to identify when these flares occur, provides us with a statistically significant temperature and emission scaling law for A and B class flares: EM = 6.1 x 10 33 T 1.9±0.1 .

  17. Observations of vector magnetic fields in flaring active regions

    Science.gov (United States)

    Chen, Jimin; Wang, Haimin; Zirin, Harold; Ai, Guoxiang

    1994-01-01

    We present vector magnetograph data of 6 active regions, all of which produced major flares. Of the 20 M-class (or above) flares, 7 satisfy the flare conditions prescribed by Hagyard (high shear and strong transverse fields). Strong photospheric shear, however, is not necessarily a condition for a flare. We find an increase in the shear for two flares, a 6-deg shear increase along the neutral line after a X-2 flare and a 13-deg increase after a M-1.9 flare. For other flares, we did not detect substantial shear changes.

  18. Radiation from Large Gas Volumes and Heat Exchange in Steam Boiler Furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, A. N., E-mail: tgtu-kafedra-ese@mail.ru [Tver State Technical University (Russian Federation)

    2015-09-15

    Radiation from large cylindrical gas volumes is studied as a means of simulating the flare in steam boiler furnaces. Calculations of heat exchange in a furnace by the zonal method and by simulation of the flare with cylindrical gas volumes are described. The latter method is more accurate and yields more reliable information on heat transfer processes taking place in furnaces.

  19. Nasal flaring as a clinical sign of respiratory acidosis in patients with dyspnea.

    Science.gov (United States)

    Zorrilla-Riveiro, José Gregorio; Arnau-Bartés, Anna; Rafat-Sellarés, Ramón; García-Pérez, Dolors; Mas-Serra, Arantxa; Fernández-Fernández, Rafael

    2017-04-01

    To determine whether the presence of nasal flaring is a clinical sign of respiratory acidosis in patients attending emergency departments for acute dyspnea. Single-center, prospective, observational study of patients aged over 15 requiring urgent attention for dyspnea, classified as level II or III according to the Andorran Triage Program and who underwent arterial blood gas test on arrival at the emergency department. The presence of nasal flaring was evaluated by two observers. Demographic and clinical variables, signs of respiratory difficulty, vital signs, arterial blood gases and clinical outcome (hospitalization and mortality) were recorded. Bivariate and multivariate analyses were performed using logistic regression models. The sample comprised 212 patients, mean age 78years (SD=12.8), of whom 49.5% were women. Acidosis was recorded in 21.2%. Factors significantly associated with the presence of acidosis in the bivariate analysis were the need for pre-hospital medical care, triage level II, signs of respiratory distress, presence of nasal flaring, poor oxygenation, hypercapnia, low bicarbonates and greater need for noninvasive ventilation. Nasal flaring had a positive likelihood ratio for acidosis of 4.6 (95% CI 2.9-7.4). In the multivariate analysis, triage level II (aOR 5.16; 95% CI: 1.91 to 13.98), the need for oxygen therapy (aOR 2.60; 95% CI: 1.13-5.96) and presence of nasal flaring (aOR 6.32; 95% CI: 2.78-14.41) were maintained as factors independently associated with acidosis. Nasal flaring is a clinical sign of severity in patients requiring urgent care for acute dyspnea, which has a strong association with acidosis and hypercapnia. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Lyman continuum observations of solar flares

    Science.gov (United States)

    Machado, M. E.; Noyes, R. W.

    1978-01-01

    A study is made of Lyman continuum observations of solar flares, using data obtained by the EUV spectroheliometer on the Apollo Telescope Mount. It is found that there are two main types of flare regions: an overall 'mean' flare coincident with the H-alpha flare region, and transient Lyman continuum kernels which can be identified with the H-alpha and X-ray kernels observed by other authors. It is found that the ground level hydrogen population in flares is closer to LTE than in the quiet sun and active regions, and that the level of Lyman continuum formation is lowered in the atmosphere from a mass column density .000005 g/sq cm in the quiet sun to .0003 g/sq cm in the mean flare, and to .001 g/sq cm in kernels. From these results the amount of chromospheric material 'evaporated' into the high temperature region is derived, which is found to be approximately 10 to the 15th g, in agreement with observations of X-ray emission measures.

  1. The sun and solar flares

    International Nuclear Information System (INIS)

    McKenna-Lawlor, S.

    1982-01-01

    The subject is discussed under the headings: the sun's core (thermonuclear reactions, energy transfer from core through radiation zone, convection zone, photosphere, chromosphere and corona); the photosphere (convection, granulation, sunspots, magnetic fields, solar cycle, rotation of the sun); solar variability and paleoclimatic records (correlation of low solar activity with increased 14 C production in atmosphere); the chromosphere and corona (turbulence, temperature, coronal streamers, energy transfer); solar flares (cosmic rays, aurorae, spectra, velocity of flares, prominences, mechanisms of flares); the solar wind. (U.K.)

  2. Lagrangian solution of supersonic real gas flows

    Science.gov (United States)

    Loh, Ching-Yuen; Liou, Meng-Sing

    1993-01-01

    The present extention of a Lagrangian approach of the Riemann solution procedure, which was originally proposed for perfect gases, to real gases, is nontrivial and requires the development of an exact real-gas Riemann solver for the Lagrangian form of the conservation laws. Calculations including complex wave interactions of various types were conducted to test the accuracy and robustness of the approach. Attention is given to the case of 2D oblique waves' capture, where a slip line is clearly in evidence; the real gas effect is demonstrated in the case of a generic engine nozzle.

  3. Flares on dMe stars: IUE and optical observations of At Mic, and comparison of far-ultraviolet stellar and solar flares

    International Nuclear Information System (INIS)

    Bromage, G.E.; Phillips, K.J.H.; Dufton, P.L.; Kingston, A.E.

    1986-01-01

    The paper concerns observations of a large flare event on the dMe star At Mic, detected by the International Ultraviolet Explorer. The far-ultraviolet spectra of the flare is compared with those of other stellar flares, and also with a large solar flare recorded by the Skylab mission in 1973. The quiescent-phase optical and ultraviolet spectrum of the same dMe flare star is discussed. (U.K.)

  4. CO2 Capture from Flue Gas using Amino Acid Salt Solutions

    DEFF Research Database (Denmark)

    Lerche, Benedicte Mai; Stenby, Erling Halfdan; Thomsen, Kaj

    2009-01-01

    difficult. Amino acid salt solutions have emerged as an alternative to the alkanolamine solutions. A number of advantages make amino acid salt solutions attractive solvents for CO2 capture from flue gas. In the present study CO2 absorption in aqueous solutions of 0.5 M potassium glycinate and 0.5 M...

  5. High School Forum. The Solution: "Derivation of the Ideal Gas Law."

    Science.gov (United States)

    Herron, J. Dudley, Ed.

    1980-01-01

    Presents responses to an earlier report concerning a procedure for the derivation of the Ideal Gas Law from Charles', Boyle's, and other gas laws. Logic errors and solutions that work are discussed. (CS)

  6. Dependence of absolute magnitudes (energies) of flares on the cluster age containing flare stars

    International Nuclear Information System (INIS)

    Parsamyan, Eh.S.

    1976-01-01

    Dependences between Δmsub(u) and msub(u) are given for the Orion, NGC 7000, Pleiades and Praesepe aggregations. Maximum absolute values of flares have been calculated for stars with different luminosities. It has been shown that the values of flares can be limited by a straight line which gives the representation on the distribution of maximum values of amplitudes for the stars with different luminosities in an aggregation. Presented are k and m 0 parameters characterizing the lines fot the Orion, NGC 7000, Pleiades and Praesepe aggregation and their age T dependence. From the dependence between k (angular coefficient of straight lines) and lgT for the aggregation with known T the age of those aggregation involving a great amount of flaring stars can be found. The age of flaring stars in the neighbourhood of the Sun has been determined. The age of UV Ceti has been shown by an order to exceed that of the rest stars

  7. DETERMINING HEATING RATES IN RECONNECTION FORMED FLARE LOOPS OF THE M8.0 FLARE ON 2005 MAY 13

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wenjuan; Qiu Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Caspi, Amir [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States)

    2013-06-20

    We analyze and model an M8.0 flare on 2005 May 13 observed by the Transition Region and Coronal Explorer and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to determine the energy release rate from magnetic reconnection that forms and heats numerous flare loops. The flare exhibits two ribbons in UV 1600 A emission. Analysis shows that the UV light curve at each flaring pixel rises impulsively within a few minutes, and decays slowly with a timescale longer than 10 minutes. Since the lower atmosphere (the transition region and chromosphere) responds to energy deposit nearly instantaneously, the rapid UV brightening is thought to reflect the energy release process in the newly formed flare loop rooted at the footpoint. In this paper, we utilize the spatially resolved (down to 1'') UV light curves and the thick-target hard X-ray emission to construct heating functions of a few thousand flare loops anchored at the UV footpoints, and compute plasma evolution in these loops using the enthalpy-based thermal evolution of loops model. The modeled coronal temperatures and densities of these flare loops are then used to calculate coronal radiation. The computed soft X-ray spectra and light curves compare favorably with those observed by RHESSI and by the Geostationary Operational Environmental Satellite X-ray Sensor. The time-dependent transition region differential emission measure for each loop during its decay phase is also computed with a simplified model and used to calculate the optically thin C IV line emission, which dominates the UV 1600 A bandpass during the flare. The computed C IV line emission decays at the same rate as observed. This study presents a method to constrain heating of reconnection-formed flare loops using all available observables independently, and provides insight into the physics of energy release and plasma heating during the flare. With this method, the lower limit of the total energy used to heat the flare loops in

  8. M DWARF FLARE CONTINUUM VARIATIONS ON ONE-SECOND TIMESCALES: CALIBRATING AND MODELING OF ULTRACAM FLARE COLOR INDICES

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Adam F. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Mathioudakis, Mihalis [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN (United Kingdom); Hawley, Suzanne L.; Hilton, Eric J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Wisniewski, John P. [HL Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks Street, Norman, OK 73019 (United States); Dhillon, Vik S. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Marsh, Tom R. [Department of Physics, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL (United Kingdom); Brown, Benjamin P., E-mail: adam.f.kowalski@nasa.gov [Laboratory for Atmospheric and Space Physics and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80309 (United States)

    2016-04-01

    We present a large data set of high-cadence dMe flare light curves obtained with custom continuum filters on the triple-beam, high-speed camera system ULTRACAM. The measurements provide constraints for models of the near-ultraviolet (NUV) and optical continuum spectral evolution on timescales of ≈1 s. We provide a robust interpretation of the flare emission in the ULTRACAM filters using simultaneously obtained low-resolution spectra during two moderate-sized flares in the dM4.5e star YZ CMi. By avoiding the spectral complexity within the broadband Johnson filters, the ULTRACAM filters are shown to characterize bona fide continuum emission in the NUV, blue, and red wavelength regimes. The NUV/blue flux ratio in flares is equivalent to a Balmer jump ratio, and the blue/red flux ratio provides an estimate for the color temperature of the optical continuum emission. We present a new “color–color” relationship for these continuum flux ratios at the peaks of the flares. Using the RADYN and RH codes, we interpret the ULTRACAM filter emission using the dominant emission processes from a radiative-hydrodynamic flare model with a high nonthermal electron beam flux, which explains a hot, T ≈ 10{sup 4} K, color temperature at blue-to-red optical wavelengths and a small Balmer jump ratio as observed in moderate-sized and large flares alike. We also discuss the high time resolution, high signal-to-noise continuum color variations observed in YZ CMi during a giant flare, which increased the NUV flux from this star by over a factor of 100.

  9. M DWARF FLARE CONTINUUM VARIATIONS ON ONE-SECOND TIMESCALES: CALIBRATING AND MODELING OF ULTRACAM FLARE COLOR INDICES

    International Nuclear Information System (INIS)

    Kowalski, Adam F.; Mathioudakis, Mihalis; Hawley, Suzanne L.; Hilton, Eric J.; Wisniewski, John P.; Dhillon, Vik S.; Marsh, Tom R.; Brown, Benjamin P.

    2016-01-01

    We present a large data set of high-cadence dMe flare light curves obtained with custom continuum filters on the triple-beam, high-speed camera system ULTRACAM. The measurements provide constraints for models of the near-ultraviolet (NUV) and optical continuum spectral evolution on timescales of ≈1 s. We provide a robust interpretation of the flare emission in the ULTRACAM filters using simultaneously obtained low-resolution spectra during two moderate-sized flares in the dM4.5e star YZ CMi. By avoiding the spectral complexity within the broadband Johnson filters, the ULTRACAM filters are shown to characterize bona fide continuum emission in the NUV, blue, and red wavelength regimes. The NUV/blue flux ratio in flares is equivalent to a Balmer jump ratio, and the blue/red flux ratio provides an estimate for the color temperature of the optical continuum emission. We present a new “color–color” relationship for these continuum flux ratios at the peaks of the flares. Using the RADYN and RH codes, we interpret the ULTRACAM filter emission using the dominant emission processes from a radiative-hydrodynamic flare model with a high nonthermal electron beam flux, which explains a hot, T ≈ 10 4 K, color temperature at blue-to-red optical wavelengths and a small Balmer jump ratio as observed in moderate-sized and large flares alike. We also discuss the high time resolution, high signal-to-noise continuum color variations observed in YZ CMi during a giant flare, which increased the NUV flux from this star by over a factor of 100

  10. Chromosphere flare models

    International Nuclear Information System (INIS)

    Avrett, E.H.; Kurucz, R.L.; Machado, M.E.; NASA, Marshall Space Flight Center, Huntsville, AL)

    1985-01-01

    Further calculated results based on the F1 and F2 chromospheric models of Machado et al. (1980) are presented in addition to results from a model with enhanced temperatures relative to the weak-flare model F1 in the upper photosphere and low chromosphere, and from a model with enhanced temperatures relative to the strong flare model F2 in the upper chromosphere. The coupled equations of statistical equilibrium and radiative transfer for H, H(-), He I-II, C I-IV, Si I-II, Mg I-II, Fe, Al, O I-II, Na, and Ca II are solved, and the overall absorption and emission of radiation by lines throughout the spectrum are determined by means of a reduced set of opacities taken from a compilation of over 10 million lines. Semiempirical models show that the white light flare continuum may arise by extreme chromospheric overheating, as well as by an enhancement of the minimum temperature region. 34 references

  11. A Bayesian method for detecting stellar flares

    Science.gov (United States)

    Pitkin, M.; Williams, D.; Fletcher, L.; Grant, S. D. T.

    2014-12-01

    We present a Bayesian-odds-ratio-based algorithm for detecting stellar flares in light-curve data. We assume flares are described by a model in which there is a rapid rise with a half-Gaussian profile, followed by an exponential decay. Our signal model also contains a polynomial background model required to fit underlying light-curve variations in the data, which could otherwise partially mimic a flare. We characterize the false alarm probability and efficiency of this method under the assumption that any unmodelled noise in the data is Gaussian, and compare it with a simpler thresholding method based on that used in Walkowicz et al. We find our method has a significant increase in detection efficiency for low signal-to-noise ratio (S/N) flares. For a conservative false alarm probability our method can detect 95 per cent of flares with S/N less than 20, as compared to S/N of 25 for the simpler method. We also test how well the assumption of Gaussian noise holds by applying the method to a selection of `quiet' Kepler stars. As an example we have applied our method to a selection of stars in Kepler Quarter 1 data. The method finds 687 flaring stars with a total of 1873 flares after vetos have been applied. For these flares we have made preliminary characterizations of their durations and and S/N.

  12. Solar and stellar flares and their impact on planets

    Science.gov (United States)

    Shibata, Kazunari

    Recent observations of the Sun revealed that the solar atmosphere is full of flares and flare-like phenomena, which affect terrestrial environment and our civilization. It has been established that flares are caused by the release of magnetic energy through magnetic reconnection. Many stars show flares similar to solar flares, and such stellar flares especially in stars with fast rotation are much more energetic than solar flares. These are called superflares. The total energy of a solar flare is 1029 - 1032 erg, while that of a superflare is 1033 - 1038 erg. Recently, it was found that superflares (with 1034 - 1035 erg) occur on Sun-like stars with slow rotation with frequency once in 800 - 5000 years. This suggests the possibility of superflares on the Sun. We review recent development of solar and stellar flare research, and briefly discuss possible impacts of superflares on the Earth and exoplanets.

  13. Energetic Particle Estimates for Stellar Flares

    Science.gov (United States)

    Youngblood, Allison; Chamberlin, Phil; Woods, Tom

    2018-01-01

    In the heliosphere, energetic particles are accelerated away from the Sun during solar flares and/or coronal mass ejections where they frequently impact the Earth and other solar system bodies. Solar (or stellar) energetic particles (SEPs) not only affect technological assets, but also influence mass loss and chemistry in planetary atmospheres (e.g., depletion of ozone). SEPs are increasingly recognized as an important factor in assessing exoplanet habitability, but we do not yet have constraints on SEP emission from any stars other than the Sun. Until indirect measurements are available, we must assume solar-like particle production and apply correlations between solar flares and SEPs detected near Earth to stellar flares. We present improved scaling relations between solar far-UV flare flux and >10 MeV proton flux near Earth. We apply these solar scaling relations to far-UV flares from exoplanet host stars and discuss the implications for modeling chemistry and mass loss in exoplanet atmospheres.

  14. Reconstruction of a Large-scale Pre-flare Coronal Current Sheet Associated with a Homologous X-shaped Flare

    Science.gov (United States)

    Jiang, Chaowei; Yan, Xiaoli; Feng, Xueshang; Duan, Aiying; Hu, Qiang; Zuo, Pingbing; Wang, Yi

    2017-11-01

    As a fundamental magnetic structure in the solar corona, electric current sheets (CSs) can form either prior to or during a solar flare, and they are essential for magnetic energy dissipation in the solar corona because they enable magnetic reconnection. However, the static reconstruction of a CS is rare, possibly due to limitations that are inherent in the available coronal field extrapolation codes. Here we present the reconstruction of a large-scale pre-flare CS in solar active region 11967 using an MHD-relaxation model constrained by the SDO/HMI vector magnetogram. The CS is associated with a set of peculiar homologous flares that exhibit unique X-shaped ribbons and loops occurring in a quadrupolar magnetic configuration.This is evidenced by an ’X’ shape, formed from the field lines traced from the CS to the photosphere. This nearly reproduces the shape of the observed flare ribbons, suggesting that the flare is a product of the dissipation of the CS via reconnection. The CS forms in a hyperbolic flux tube, which is an intersection of two quasi-separatrix layers. The recurrence of the X-shaped flares might be attributed to the repetitive formation and dissipation of the CS, as driven by the photospheric footpoint motions. These results demonstrate the power of a data-constrained MHD model in reproducing a CS in the corona as well as providing insight into the magnetic mechanism of solar flares.

  15. Foretelling Flares and Solar Energetic Particle Events: the FORSPEF tool

    Science.gov (United States)

    Anastasiadis, Anastasios; Papaioannou, Athanasios; Sandberg, Ingmar; Georgoulis, Manolis K.; Tziotziou, Kostas; Jiggens, Piers

    2017-04-01

    the Sun and the interplanetary space, while the combined usage of SF and SEP forecasting methods upgrades FORSPEF to an integrated forecasting solution. Finally, we demonstrate the validation of the modules of the FORSPEF tool using categorical scores constructed on archived data and we further discuss independent case studies. This work has been funded through the "FORSPEF: FORecasting Solar Particle Events and Flares", ESA Contract No. 4000109641/13/NL/AK and the "SPECS: Solar Particle Events foreCasting Studies" project of the National Observatory of Athens.

  16. Infrared spectroscopy for monitoring gas hydrates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, G.T.; Luzinova, Y.; Mizaikoff, B. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry; Raichlin, Y.; Katzir, A. [Tel-Aviv Univ., Tel-Aviv (Israel). Shool of Physics and Astronomy

    2008-07-01

    This paper introduced the first principles for monitoring gas hydrate formation and dissociation in aqueous solution by evaluating state-responsive infrared (IR) absorption features of water with fiberoptic evanescent field spectroscopy. A first order linear functional relationship was also derived according to Lambert Beer's law in order to quantify the percentage gas hydrate within the volume of water probed via the evanescent field. In addition, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components. As such, evanescent field sensing strategies were established as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments. 21 refs., 5 figs.

  17. Cloud Ablation by a Relativistic Jet and the Extended Flare in CTA 102 in 2016 and 2017

    Science.gov (United States)

    Zacharias, M.; Böttcher, M.; Jankowsky, F.; Lenain, J.-P.; Wagner, S. J.; Wierzcholska, A.

    2017-12-01

    In late 2016 and early 2017, the flat spectrum radio quasar CTA 102 exhibited a very strong and long-lasting outburst. The event can be described by a roughly two-month long increase of the baseline flux in the monitored energy bands (optical to γ-rays) by a factor 8, and a subsequent decrease over another two months back to pre-flare levels. The long-term trend was superseded by short but very strong flares, resulting in a peak flux that was a factor 50 above pre-flare levels in the γ-ray domain and almost a factor 100 above pre-flare levels in the optical domain. In this paper, we explain the long-term evolution of the outburst by the ablation of a gas cloud penetrating the relativistic jet. The slice-by-slice ablation results in a gradual increase of the particle injection until the center of the cloud is reached, after which the injected number of particles decreases again. With reasonable cloud parameters, we obtain excellent fits of the long-term trend.

  18. Challenges and solutions in natural gas engine development and productions

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, Mahdi; Izanloo, Hossein [Irankhodro Powertrain Co. (IPCO) (Iran)

    2008-07-01

    As an alternative fuel, natural gas is generally accepted for internal combustion engines and some developments have been conducted in order to adopt it for the road vehicles and stationary applications. Foresights shows natural gas vehicles will be a part of the future transportation technology regarding to their mid and long-term benefits. Therefore inherent problems of natural gas engine technology should be overcome to produce a competitive engine. In this paper major problems and their possible solutions in developing and producing natural gas engine for passenger cars are detailed and discussed. Challenging materials are sorted and presented in two categorizes: technical and econo-strategical problems. In the technical section major difficulties faced in components or systems of natural gas engine are analysed in different aspects of design, validation, and production. In addition problems arisen from the fuel characteristics which influence the function and durability of engine are argued. Subjects like freezing in gas regulator, cold start fuel injection, gas leakage, impurities within compressed natural gas, variation in fuel composition, thermo-mechanics of cylinder head and block, wear of valve seat inserts, spark plug erosion, back-fire phenomenon, engine oil quality requirement, low power density and mileage are described. In the econo-strategical discussion, challenges like limited gas distribution infrastructure, lack of specific manufacturing standards and codes, and non-dedicated emission standards are explained. In both part of the paper a comprehensive view is extended to clarify the effect, risk and solutions of each problem. Due to the fact that almost all information and analysis presented in this paper are based on the experience of developing a natural gas engine family, and an extensive literature review, discussions and conclusions could be useful as a guide line for future natural gas engine projects. (orig.)

  19. Risk Analysis of Flare Flame-out Condition in a Gas Process Facility Analyse des risques des conditions d’extinction de torche au sein d’une installation de traitement de gaz

    Directory of Open Access Journals (Sweden)

    Zadakbar O.

    2011-02-01

    Full Text Available Flaring is a common method of disposal of flammable waste gases in the downstream industries. Flare flame out (flame lift-off or blow-outs often occurs causing toxic vapors to discharge. The toxic gases released may have hazardous effects on the surrounding environment. To study the effect of inhalation exposure of these toxic gases on human health, the four steps of the EPA (Environmental Protection Agency framework with the field data to quantify the cancer and non-cancer health risks are integrated in this paper. As a part of exposure assessment, gas dispersion modeling using AERMOD and UDM-PHAST is applied in two different conditions of normal flaring and flare flame out during a particular climate condition in Khangiran region. Recommendations to avoid flare flame out conditions are also presented here. Le torchage est un procédé courant d’élimination des gaz résiduaires inflammables dans les industries de traitement. L’extinction de la torche (par décollage ou soufflage de flamme provoque souvent une émission de vapeurs toxiques. Ces gaz toxiques libérés peuvent présenter des effets dangereux sur le milieu environnant. Pour étudier l’effet d’une exposition par inhalation de ces gaz toxiques sur la santé, cet article croise les quatre étapes de la démarche de l’EPA (Environmental Protection Agency, Agence de protection de l’environnement avec les données d’exploitation afin de quantifier le risque sanitaire cancérologique et non cancérologique. Dans le cadre de l’estimation d’exposition, une modélisation de dispersion des gaz utilisant AERMOD et UDM-PHAST est évaluée dans deux configurations différentes de torchage normal et d’extinction de torche à l’occasion de conditions climatiques particulières dans la région du Khangiran. L’article propose également des recommandations destinées à éviter les conditions d’une extinction de flamme de torche.

  20. Thermal Structure of Supra-Arcade Plasma in Two Solar Flares

    Science.gov (United States)

    Reeves, Katharine K.; Savage, Sabrina; McKenzie, David E.; Weber, Mark A.

    2012-01-01

    In this work, we use Hinode/XRT and SDO/AIA data to determine the thermal structure of supra-arcade plasma in two solar flares. The first flare is a Ml.2 flare that occurred on November 5, 2010 on the east limb. This flare was one of a series of flares from AR 11121, published in Reeves & Golub (2011). The second flare is an XI.7 flare that occurred on January 27, 2012 on the west limb. This flare exhibits visible supra-arcade downflows (SADs), where the November 2010 flare does not. For these two flares we combine XRT and AlA data to calculate DEMs of each pixel in the supra-arcade plasma, giving insight into the temperature and density structures in the fan of plasma above the post-flare arcade. We find in each case that the supra-arcade plasma is around 10 MK, and there is a marked decrease in the emission measure in the SADs. We also compare the DEMs calculated with the combined AIA/XRT dataset to those calculated using AIA alone.

  1. Flare research with the NASA/MSFC vector magnetograph - Observed characteristics of sheared magnetic fields that produce flares

    Science.gov (United States)

    Moore, R. L.; Hagyard, M. J.; Davis, J. M.

    1987-01-01

    The present MSFC Vector Magnetograph has sufficient spatial resolution (2.7 arcsec pixels) and sensitivity to the transverse field (the noise level is about 100 gauss) to map the transverse field in active regions accurately enough to reveal key aspects of the sheared magnetic fields commonly found at flare sites. From the measured shear angle along the polarity inversion line in sites that flared and in other shear sites that didn't flare, evidence is found that a sufficient condition for a flare to occur in 1000 gauss fields in and near sunspots is that both: (1) the maximum shear angle exceed 85 degrees; and (2) the extent of strong shear (shear angle of greater than 80 degrees) exceed 10,000 km.

  2. Identifying core domains to assess flare in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Bartlett, Susan J; Hewlett, Sarah; Bingham, Clifton O

    2012-01-01

    For rheumatoid arthritis (RA), there is no consensus on how to define and assess flare. Variability in flare definitions impairs understanding of findings across studies and limits ability to pool results. The OMERACT RA Flare Group sought to identify domains to define RA flares from patient...

  3. A study of flare stars in the taurus region

    International Nuclear Information System (INIS)

    Khodzhaev, A.S.

    1986-01-01

    The results are given of a search for flare stars in the region of the dark clouds in Taurus together with the results of photometric, H /sub alpha/ -spectroscopic, and statistical investigations of them. Photographic observations during 1980-1984 revealed 92 new flare stars, 13 of which were found to be known Orion variables with 16 repeated flares of 13 previously known flare stars. Their apparent distribution is considered. The question of whether the flare stars belong to a dark cloud is discussed. A comparative analysis of the flare stars in the Taurus region and other aggregates is made. The Hertzsprung-Russell (V, B - V) and two-color (U - B, B - V) diagrams for the flare stars are similar to the corresponding diagrams constructed for star clusters and associations (Pleiades, Orion, etc.). The total number of flare stars in the region of the dark clouds in Taurus is estimated at ≥ 500

  4. WHITE-LIGHT FLARES ON CLOSE BINARIES OBSERVED WITH KEPLER

    International Nuclear Information System (INIS)

    Gao, Qing; Xin, Yu; Liu, Ji-Feng; Zhang, Xiao-Bin; Gao, Shuang

    2016-01-01

    Based on Kepler data, we present the results of a search for white light flares on 1049 close binaries. We identify 234 flare binaries, of which 6818 flares are detected. We compare the flare-binary fraction in different binary morphologies (“detachedness”). The result shows that the fractions in over-contact and ellipsoidal binaries are approximately 10%–20% lower than those in detached and semi-detached systems. We calculate the binary flare activity level (AL) of all the flare binaries, and discuss its variations along the orbital period ( P orb ) and rotation period ( P rot , calculated for only detached binaries). We find that the AL increases with decreasing P orb or P rot , up to the critical values at P orb ∼ 3 days or P rot ∼ 1.5 days, and thereafter the AL starts decreasing no matter how fast the stars rotate. We examine the flaring rate as a function of orbital phase in two eclipsing binaries on which a large number of flares are detected. It appears that there is no correlation between flaring rate and orbital phase in these two binaries. In contrast, when we examine the function with 203 flares on 20 non-eclipse ellipsoidal binaries, bimodal distribution of amplitude-weighted flare numbers shows up at orbital phases 0.25 and 0.75. Such variation could be larger than what is expected from the cross section modification.

  5. Generation Mechanisms of Quasi-parallel and Quasi-circular Flare Ribbons in a Confined Flare

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Perez, Aaron; Thalmann, Julia K.; Veronig, Astrid M.; Dickson, Ewan C. [IGAM/Institute of Physics, University of Graz, A-8010 Graz (Austria); Su, Yang [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing (China); Gömöry, Peter, E-mail: aaron.hernandez-perez@uni-graz.at [Astronomical Institute, Slovak Academy of Sciences, 05960 Tatranská Lomnica (Slovakia)

    2017-10-01

    We analyze a confined multiple-ribbon M2.1 flare (SOL2015-01-29T11:42) that originated from a fan-spine coronal magnetic field configuration, within active region NOAA 12268. The observed ribbons form in two steps. First, two primary ribbons form at the main flare site, followed by the formation of secondary ribbons at remote locations. We observe a number of plasma flows at extreme-ultraviolet temperatures during the early phase of the flare (as early as 15 minutes before the onset) propagating toward the formation site of the secondary ribbons. The secondary ribbon formation is co-temporal with the arrival of the pre-flare generated plasma flows. The primary ribbons are co-spatial with Ramaty High Energy Spectroscopic Imager ( RHESSI ) hard X-ray sources, whereas no enhanced X-ray emission is detected at the secondary ribbon sites. The (E)UV emission, associated with the secondary ribbons, peaks ∼1 minute after the last RHESSI hard X-ray enhancement. A nonlinear force-free model of the coronal magnetic field reveals that the secondary flare ribbons are not directly connected to the primary ribbons, but to regions nearby. Detailed analysis suggests that the secondary brightenings are produced due to dissipation of kinetic energy of the plasma flows (heating due to compression), and not due to non-thermal particles accelerated by magnetic reconnection, as is the case for the primary ribbons.

  6. Frequency distribution function of stellar flares in the Orion association

    International Nuclear Information System (INIS)

    Parsamian, E.S.

    1981-01-01

    The temporal distributions of flare stars in the Orion association and the numbers of stars with different flare frequencies are determined by means of Ambartsumian's (1978) method, which uses the chronology of discovery of 'first' flares and the chronology of confirmations, i.e., the temporal distributions of 'repeated' flares. It is shown that flare stars with high flare frequency (not greater than 1000 hours) in the Pleiades are basically stars of low luminosity with M(U) not less than 13m. Two independent methods of determining the number of flare stars in the aggregates confirm that there are about 1.5 times more flare stars in the Orion association than in the Pleiades

  7. Radon Concentration in Outdoors and Indoors Around the Flare in Oil Mine Sites

    International Nuclear Information System (INIS)

    Sutarman; Wahyudi; Luhantara

    2003-01-01

    The flares are much found at the oil exploration areas which appear the combustion gases emission to the environment that pass through a pipe at about 8 m high from the ground level. The flare is released into the environment together with the hydrocarbon and radon gases. This study has been carried out the measurement of the radon gas concentration only. Radon is a radioactive gas which comes from the natural radioactive decay of uranium ( 238 U). The outdoor radon concentrations were measured in 23 locations with the two-filter method. The locations were determined by a circle which the flare as the point center. The outdoor radon concentrations were measured in 74 houses (more than distance of 600 m from the flare) with the alpha track detector (CR-39) placed in the living rooms for about three months. The measurements of the radon concentrations were carried out in Cepu, Cirebon, and Prabumulih oil mine sites. The results showed that the outdoor radon concentrations a range of 108 Bq/m 3 to 256 Bq/m 3 in Cepu, 248 Bq/m 3 to 3525 Bq/m 3 in Cirebon, and 51 Bq/m 3 to 114 Bq/m 3 in Prabumulih. The results showed that the indoor radon concentrations a range of 11 Bq/m 3 to 38 Bq/m 3 in Cepu, 28 Bq/m 3 to 184 Bq/m 3 in Cirebon, and 12 Bq/m 3 to 38 Bq/m 3 in Prabumulih. The data of the maximum radon concentration in outdoor air was higher than an actual level which recommended by International Atomic Energy Agency (IAEA) for workplaces. The maximum radon concentration in indoor air was lower than an actual level which recommended by IAEA for dwellings. IAEA recommends the actual level of 1000 Bq/m 3 for workplaces and 200 Bq/m 3 for dwellings. These data will be used for the baseline data of the environmental radioactivity in Indonesia. (author)

  8. Study on the flare stars in the Taurus region

    International Nuclear Information System (INIS)

    Khodzhaev, A.S.

    1986-01-01

    The results of the search of flare stars and their photometric, Hsub(α)-spectroscopic and statistical study in the Taurus are presented. By means of photographic observations carried out during 1980-1984, 92 new flare stars were discovered, 13 of which are known Orion Population variables, and 16 repeated flare-ups among 13 known flare stars. Spatial distribution of these stars was considered and the problem of their membership was discussed. Comparative analysis of the data of flare stars in the Taurus with that of other systems has been carried out. The Herzsprung-Russel and two-colour (U-B, B-V) diagrams for the Taurus flare stars are similar to the diagrams of stellar clusters and associations (Pleiades, Orion etc.). The estimated total number of flare stars in this region is larger than 500

  9. A New Paradigm for Flare Particle Acceleration

    Science.gov (United States)

    Guidoni, Silvina E.; Karpen, Judith T.; DeVore, C. Richard

    2017-08-01

    The mechanism that accelerates particles to the energies required to produce the observed high-energy impulsive emission and its spectra in solar flares is not well understood. Here, we propose a first-principle-based model of particle acceleration that produces energy spectra that closely resemble those derived from hard X-ray observations. Our mechanism uses contracting magnetic islands formed during fast reconnection in solar flares to accelerate electrons, as first proposed by Drake et al. (2006) for kinetic-scale plasmoids. We apply these ideas to MHD-scale islands formed during fast reconnection in a simulated eruptive flare. A simple analytic model based on the particles’ adiabatic invariants is used to calculate the energy gain of particles orbiting field lines in our ultrahigh-resolution, 2.5D, MHD numerical simulation of a solar eruption (flare + coronal mass ejection). Then, we analytically model electrons visiting multiple contracting islands to account for the observed high-energy flare emission. Our acceleration mechanism inherently produces sporadic emission because island formation is intermittent. Moreover, a large number of particles could be accelerated in each macroscopic island, which may explain the inferred rates of energetic-electron production in flares. We conclude that island contraction in the flare current sheet is a promising candidate for electron acceleration in solar eruptions. This work was supported in part by the NASA LWS and H-SR programs..

  10. Sulphur recovery and sulphur emissions at Alberta sour gas plants : annual report for 2005

    International Nuclear Information System (INIS)

    2005-01-01

    The sulphur recovery of Alberta's grandfathered sour gas plants is monitored by the Alberta Energy and Utilities Board. This report provides an annual summary of industry performance for sulphur recovery at large acid gas flaring sour gas plants, and sulphur recovery at all acid gas injection sour gas plants. It follows Interim Directive (ID) 2001-3 which stipulates guidelines for sulphur recovery for the province of Alberta. It includes a list of grandfathered and non grandfathered plants in Alberta. Grandfathered sulphur recovery plants that exceed expectations have the option to file a sulphur emission performance credit report and can use the credits to meet some of their sulphur requirement in the future. Acid gas flaring plants face more stringent requirements and cannot earn credits. Several plants have degrandfathered in the past 5 years. Eleven have made upgrades, 4 have been relicensed to meet the requirements for new plants, and 4 have shut down. Forty-one grandfathered plants remain. Sulphur emissions have decreased 39 per cent for grandfathered acid gas flaring plants, and 28 per cent for grandfathered sulphur recovery plants. 10 tabs., 3 figs

  11. Acoustic mapping of shallow water gas releases using shipborne multibeam systems

    Science.gov (United States)

    Urban, Peter; Köser, Kevin; Weiß, Tim; Greinert, Jens

    2015-04-01

    Water column imaging (WCI) shipborne multibeam systems are effective tools for investigating marine free gas (bubble) release. Like single- and splitbeam systems they are very sensitive towards gas bubbles in the water column, and have the advantage of the wide swath opening angle, 120° or more allowing a better mapping and possible 3D investigations of targets in the water column. On the downside, WCI data are degraded by specific noise from side-lobe effects and are usually not calibrated for target backscattering strength analysis. Most approaches so far concentrated on manual investigations of bubbles in the water column data. Such investigations allow the detection of bubble streams (flares) and make it possible to get an impression about the strength of detected flares/the gas release. Because of the subjective character of these investigations it is difficult to understand how well an area has been investigated by a flare mapping survey and subjective impressions about flare strength can easily be fooled by the many acoustic effects multibeam systems create. Here we present a semi-automated approach that uses the behavior of bubble streams in varying water currents to detect and map their exact source positions. The focus of the method is application of objective rules for flare detection, which makes it possible to extract information about the quality of the seepage mapping survey, perform automated noise reduction and create acoustic maps with quality discriminators indicating how well an area has been mapped.

  12. Gas-solute dispersivity ratio in granular porous media as related to particle size distribution and particle shape

    DEFF Research Database (Denmark)

    Pugliese, Lorenzo; Poulsen, Tjalfe; Straface, Salvatore

    2013-01-01

    Measurements of solute dispersion in porous media is generally much more time consuming than gas dispersion measurements performed under equivalent conditions. Significant time savings may therefore, be achieved if solute dispersion coefficients can be estimated based on measured gas dispersion...... data. This paper evaluates the possibility for estimating solute dispersion based on gas dispersion measurements. Breakthrough measurements were carried out at different fluid velocities (covering the same range in Reynolds number), using O2 and NaCl as gas and solute tracers, respectively. Three...... different, granular porous materials were used: (1) crushed granite (very angular particles), (2) gravel (particles of intermediate roundness) and (3) Leca® (almost spherical particles). For each material, 21 different particle size fractions were used. Gas and solute dispersion coefficients were determined...

  13. New Results from the Flare Genesis Experiment

    Science.gov (United States)

    Rust, D. M.; Bernasconi, P. N.; Eaton, H. A.; Keller, C.; Murphy, G. A.; Schmieder, B.

    2000-05-01

    From January 10 to 27, 2000, the Flare Genesis solar telescope observed the Sun while suspended from a balloon in the stratosphere above Antarctica. The goal of the mission was to acquire long time series of high-resolution images and vector magnetograms of the solar photosphere and chromosphere. Images were obtained in the magnetically sensitive Ca I line at 6122 Angstroms and at H-alpha (6563 Angstroms). The FGE data were obtained in the context of Max Millennium Observing Campaign #004, the objective of which was to study the ``Genesis of Solar Flares and Active Filaments/Sigmoids." Flare Genesis obtained about 26,000 usable images on the 8 targeted active regions. A preliminary examination reveals a good sequence on an emerging flux region and data on the M1 flare on January 22, as well as a number of sequences on active filaments. We will present the results of our first analysis efforts. Flare Genesis was supported by NASA grants NAG5-4955, NAG5-5139, and NAG5-8331 and by NSF grant OPP-9615073. The Air Force Office of Scientific Research and the Ballistic Missile Defense Organization supported early development of the Flare Genesis Experiment.

  14. An Interactive Multi-instrument Database of Solar Flares

    Energy Technology Data Exchange (ETDEWEB)

    Sadykov, Viacheslav M; Kosovichev, Alexander G; Oria, Vincent; Nita, Gelu M [Center for Computational Heliophysics, New Jersey Institute of Technology, Newark, NJ 07102 (United States)

    2017-07-01

    Solar flares are complicated physical phenomena that are observable in a broad range of the electromagnetic spectrum, from radio waves to γ -rays. For a more comprehensive understanding of flares, it is necessary to perform a combined multi-wavelength analysis using observations from many satellites and ground-based observatories. For an efficient data search, integration of different flare lists, and representation of observational data, we have developed the Interactive Multi-Instrument Database of Solar Flares (IMIDSF, https://solarflare.njit.edu/). The web-accessible database is fully functional and allows the user to search for uniquely identified flare events based on their physical descriptors and the availability of observations by a particular set of instruments. Currently, the data from three primary flare lists ( Geostationary Operational Environmental Satellites , RHESSI , and HEK) and a variety of other event catalogs ( Hinode , Fermi GBM, Konus- W IND, the OVSA flare catalogs, the CACTus CME catalog, the Filament eruption catalog) and observing logs ( IRIS and Nobeyama coverage) are integrated, and an additional set of physical descriptors (temperature and emission measure) is provided along with an observing summary, data links, and multi-wavelength light curves for each flare event since 2002 January. We envision that this new tool will allow researchers to significantly speed up the search of events of interest for statistical and case studies.

  15. Solar and Stellar Flares and Their Effects on Planets

    Science.gov (United States)

    Shibata, Kazunari

    2015-08-01

    Recent space observations of the Sun revealed that the solar atmosphere is full of explosions, such as flares and flare-like phenomena. These flares generate not only strong electromagnetic emissions but also nonthermal particles and bulk plasma ejections, which sometimes lead to geomagnetic storms and affect terrestrial environment and our civilization, damaging satellite, power-grids, radio communication etc. Solar flares are prototype of various explosions in our universe, and hence are important not only for geophysics and environmental science but also for astrophysics. The energy source of solar flares is now established to be magnetic energy stored near sunspots. There is now increasing observational evidence that solar flares are caused by magnetic reconnection, merging of anti-parallel magnetic field lines and associated magneto-plasma dynamics (Shibata and Magara 2011, Living Review). It has also been known that many stars show flares similar to solar flares, and often such stellar flares are much more energetic than solar flares. The total energy of a solar flare is typically 10^29 - 10^32 erg. On the other hand, there are much more energetic flares (10^33 - 10^38 erg) in stars, especially in young stars. These are called superflares. We argue that these superflares on stars can also be understood in a unified way based on the reconnection mechanism. Finally we show evidence of occurrence of superflares on Sun-like stars according to recent stellar observations (Maehara et al. 2012, Nature, Shibayama et al. 2013), which revealed that superflares with energy of 10^34 - 10^35 erg (100 - 1000 times of the largest solar flares) occur with frequency of once in 800 - 5000 years on Sun-like stars which are very similar to our Sun. Against the previous belief, these new observations as well as theory (Shibata et al. 2013) suggest that we cannot deny the possibility of superflares on the present Sun. Finally, we shall discuss possible impacts of these superflares

  16. MOST OBSERVATIONS OF OUR NEAREST NEIGHBOR: FLARES ON PROXIMA CENTAURI

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, James R. A. [Department of Physics and Astronomy, Western Washington University, 516 High Street, Bellingham, WA 98225 (United States); Kipping, David M. [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Sasselov, Dimitar [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Matthews, Jaymie M. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Cameron, Chris [Department of Mathematics, Physics and Geology, Cape Breton University, 1250 Grand Lake Road, Sydney, NS B1P 6L2 (Canada)

    2016-10-01

    We present a study of white-light flares from the active M5.5 dwarf Proxima Centauri using the Canadian microsatellite Microvariability and Oscillations of STars . Using 37.6 days of monitoring data from 2014 to 2015, we have detected 66 individual flare events, the largest number of white-light flares observed to date on Proxima Cen. Flare energies in our sample range from 10{sup 29} to 10{sup 31.5} erg. The flare rate is lower than that of other classic flare stars of a similar spectral type, such as UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth. Proxima Cen does have an unusually high flare rate given its slow rotation period, however. Extending the observed power-law occurrence distribution down to 10{sup 28} erg, we show that flares with flux amplitudes of 0.5% occur 63 times per day, while superflares with energies of 10{sup 33} erg occur ∼8 times per year. Small flares may therefore pose a great difficulty in searches for transits from the recently announced 1.27 M {sub ⊕} Proxima b, while frequent large flares could have significant impact on the planetary atmosphere.

  17. Observation of solar flare by Hinotori SXT/HXM

    International Nuclear Information System (INIS)

    Ohki, Ken-ichiro; Takakura, Tatsuo; Tsuneta, Sukehisa; Nitta, Nariaki; Makishima, Kazuo.

    1982-01-01

    Solar flares were observed by SXT (hard X-ray two-dimensional observation system) and HXM (hard X-ray spectrometer) on Hinotori. The results of two-dimensional analysis of 20 flares are reported in this paper. Various images of hard X-ray were observed. Hard X-ray bursts with relatively long duration may be generated in corona. The hard X-ray flare generated on the solar disc gives information on the relative position to the H flare. The examples of this hard X-ray images are presented. The HXM can observe the hard X-ray spectra up to 350 keV. The flares with duration less than 5 min have the spectra coninciding with the thermal radiation from a single temperature before the peak, and power law type non-thermal radiation spectra after the peak. The hard X-ray flares with duration longer than 10 min have power law type spectra. (Kato, T.)

  18. Narrow-band radio flares from red dwarf stars

    Science.gov (United States)

    White, Stephen M.; Kundu, Mukul R.; Jackson, Peter D.

    1986-01-01

    VLA observations of narrow-band behavior in 20 cm flares from two red dwarf stars, L726 - 8A and AD Leo, are reported. The flare on L726 - 8A was observed at 1415 and 1515 MHz; the flux and the evolution differed significantly at the two frequencies. The flare on AD Leo lasted for 2 hr at 1415 MHz but did not appear at 1515 MHz. The AD Leo flare appears to rule out a source drifting through the stellar corona and is unlikely to be due to plasma emission. In the cyclotron maser model the narrow-band behavior reflects the range of magnetic fields present within the source. The apparent constancy of this field for 2 hr is difficult to understand if magnetic reconnection is the source of energy for the flare. The consistent polarization exhibited by red dwarf flares at 20 cm may be related to stellar activity cycles, and changes in this polarization will permit measuring the length of these cycles.

  19. Interactive Multi-Instrument Database of Solar Flares

    Science.gov (United States)

    Ranjan, Shubha S.; Spaulding, Ryan; Deardorff, Donald G.

    2018-01-01

    The fundamental motivation of the project is that the scientific output of solar research can be greatly enhanced by better exploitation of the existing solar/heliosphere space-data products jointly with ground-based observations. Our primary focus is on developing a specific innovative methodology based on recent advances in "big data" intelligent databases applied to the growing amount of high-spatial and multi-wavelength resolution, high-cadence data from NASA's missions and supporting ground-based observatories. Our flare database is not simply a manually searchable time-based catalog of events or list of web links pointing to data. It is a preprocessed metadata repository enabling fast search and automatic identification of all recorded flares sharing a specifiable set of characteristics, features, and parameters. The result is a new and unique database of solar flares and data search and classification tools for the Heliophysics community, enabling multi-instrument/multi-wavelength investigations of flare physics and supporting further development of flare-prediction methodologies.

  20. Anti-neutrino imprint in solar neutrino flare

    Science.gov (United States)

    Fargion, D.

    2006-10-01

    A future neutrino detector at megaton mass might enlarge the neutrino telescope thresholds revealing cosmic supernova background and largest solar flares (SFs) neutrinos. Indeed the solar energetic (Ep>100 MeV) flare particles (protons, α), while scattering among themselves on solar corona atmosphere must produce prompt charged pions, whose chain decays are source of a solar (electron muon) neutrino 'flare' (at tens or hundreds MeV energy). These brief (minutes) neutrino 'bursts' at largest flare peak may overcome by three to five orders of magnitude the steady atmospheric neutrino noise on the Earth, possibly leading to their detection above detection thresholds (in a full mixed three flavour state). Moreover the birth of anti-neutrinos at a few tens of MeV very clearly flares above a null thermal 'hep' anti-neutrino solar background and also above a tiny supernova relic and atmospheric noise. The largest prompt solar anti-neutrino 'burst' may be well detected in future Super Kamikande (gadolinium implemented) anti-neutrino \\bar\

  1. Motion of matter in flare loops of the solar disc

    International Nuclear Information System (INIS)

    Xu Ao-ao

    1987-01-01

    By using the optical observation data of a Class 3B double-ribbon flare obtained on July 14, 1980 at the Yunan Observatory, and the x-ray result from the SMM satellite for the same flare, the law of motion of matter in the flare loops of the solar disc is discussed. First, the solar disc positions from the Hα and x-ray images for the flare were compared, and the altitude of the flare loop was determined according to projection effects. Second, the line-of-sight velocity distribution in the region of flare activity due to the falling of matter in the flare loop was estimated theoretically. The result agreed with the observed data

  2. Two-phase Heating in Flaring Loops

    Science.gov (United States)

    Zhu, Chunming; Qiu, Jiong; Longcope, Dana W.

    2018-03-01

    We analyze and model a C5.7 two-ribbon solar flare observed by the Solar Dynamics Observatory, Hinode, and GOES on 2011 December 26. The flare is made of many loops formed and heated successively over one and half hours, and their footpoints are brightened in the UV 1600 Å before enhanced soft X-ray and EUV missions are observed in flare loops. Assuming that anchored at each brightened UV pixel is a half flaring loop, we identify more than 6700 half flaring loops, and infer the heating rate of each loop from the UV light curve at the footpoint. In each half loop, the heating rate consists of two phases: intense impulsive heating followed by a low-rate heating that is persistent for more than 20 minutes. Using these heating rates, we simulate the evolution of their coronal temperatures and densities with the model of the “enthalpy-based thermal evolution of loops.” In the model, suppression of thermal conduction is also considered. This model successfully reproduces total soft X-ray and EUV light curves observed in 15 passbands by four instruments GOES, AIA, XRT, and EVE. In this flare, a total energy of 4.9 × 1030 erg is required to heat the corona, around 40% of this energy is in the slow-heating phase. About two-fifths of the total energy used to heat the corona is radiated by the coronal plasmas, and the other three fifth transported to the lower atmosphere by thermal conduction.

  3. Long-term hemispheric variation of the flare index

    International Nuclear Information System (INIS)

    Feng Song; Deng Lin-Hua; Xu Shi-Chun

    2013-01-01

    The long-term hemispheric variation of the flare index is investigated. It is found that, (1) the phase difference of the flare index between the northern and southern hemispheres is about 6–7 months, which is near the time delay between flare activity and sunspot activity; (2) both the dominant and phase-leading hemisphere of the flare index is the northern hemisphere in the considered time interval, implying that the hemispheric asynchrony of solar activity has a close connection with the N-S asymmetry of solar activity. (research papers)

  4. 75 FR 20271 - Oil and Gas and Sulphur Operations in the Outer Continental Shelf-Oil and Gas Production...

    Science.gov (United States)

    2010-04-19

    ... decrease in pressure, an increase in temperature, or both) from storage vessels or other low-pressure... pressures. We explain the length of time that gas may be flared or vented for each situation and clarify... the resource that is lost and the volume of greenhouse gas emissions these practices contribute to the...

  5. M Dwarf Flare Continuum Variations on One-second Timescales: Calibrating and Modeling of ULTRACAM Flare Color Indices

    Science.gov (United States)

    Kowalski, Adam F.; Mathioudakis, Mihalis; Hawley, Suzanne L.; Wisniewski, John P.; Dhillon, Vik S.; Marsh, Tom R.; Hilton, Eric J.; Brown, Benjamin P.

    2016-04-01

    We present a large data set of high-cadence dMe flare light curves obtained with custom continuum filters on the triple-beam, high-speed camera system ULTRACAM. The measurements provide constraints for models of the near-ultraviolet (NUV) and optical continuum spectral evolution on timescales of ≈1 s. We provide a robust interpretation of the flare emission in the ULTRACAM filters using simultaneously obtained low-resolution spectra during two moderate-sized flares in the dM4.5e star YZ CMi. By avoiding the spectral complexity within the broadband Johnson filters, the ULTRACAM filters are shown to characterize bona fide continuum emission in the NUV, blue, and red wavelength regimes. The NUV/blue flux ratio in flares is equivalent to a Balmer jump ratio, and the blue/red flux ratio provides an estimate for the color temperature of the optical continuum emission. We present a new “color-color” relationship for these continuum flux ratios at the peaks of the flares. Using the RADYN and RH codes, we interpret the ULTRACAM filter emission using the dominant emission processes from a radiative-hydrodynamic flare model with a high nonthermal electron beam flux, which explains a hot, T ≈ 104 K, color temperature at blue-to-red optical wavelengths and a small Balmer jump ratio as observed in moderate-sized and large flares alike. We also discuss the high time resolution, high signal-to-noise continuum color variations observed in YZ CMi during a giant flare, which increased the NUV flux from this star by over a factor of 100. Based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium, based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsica de Canarias, and observations, and based on observations made with the ESO Telescopes

  6. Does the stellar distribution flare? A comparison of stellar scale heights with LAB H I data

    Energy Technology Data Exchange (ETDEWEB)

    Kalberla, P. M. W.; Kerp, J.; Dedes, L. [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn (Germany); Haud, U., E-mail: pkalberla@astro.uni-bonn.de [Tartu Observatory, 61602 Tõravere (Estonia)

    2014-10-10

    The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  7. Solar Flare Aimed at Earth

    Science.gov (United States)

    2002-01-01

    At the height of the solar cycle, the Sun is finally displaying some fireworks. This image from the Solar and Heliospheric Observatory (SOHO) shows a large solar flare from June 6, 2000 at 1424 Universal Time (10:24 AM Eastern Daylight Savings Time). Associated with the flare was a coronal mass ejection that sent a wave of fast moving charged particles straight towards Earth. (The image was acquired by the Extreme ultaviolet Imaging Telescope (EIT), one of 12 instruments aboard SOHO) Solar activity affects the Earth in several ways. The particles generated by flares can disrupt satellite communications and interfere with power transmission on the Earth's surface. Earth's climate is tied to the total energy emitted by the sun, cooling when the sun radiates less energy and warming when solar output increases. Solar radiation also produces ozone in the stratosphere, so total ozone levels tend to increase during the solar maximum. For more information about these solar flares and the SOHO mission, see NASA Science News or the SOHO home page. For more about the links between the sun and climate change, see Sunspots and the Solar Max. Image courtesy SOHO Extreme ultaviolet Imaging Telescope, ESA/NASA

  8. Radio-flaring Ultracool Dwarf Population Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Route, Matthew, E-mail: mroute@purdue.edu [Department of Astronomy and Astrophysics, the Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2017-08-10

    Over a dozen ultracool dwarfs (UCDs), low-mass objects of spectral types ≥M7, are known to be sources of radio flares. These typically several-minutes-long radio bursts can be up to 100% circularly polarized and have high brightness temperatures, consistent with coherent emission via the electron cyclotron maser operating in approximately kilogauss magnetic fields. Recently, the statistical properties of the bulk physical parameters that describe these UCDs have become described adequately enough to permit synthesis of the population of radio-flaring objects. For the first time, I construct a Monte Carlo simulator to model the population of these radio-flaring UCDs. This simulator is powered by Intel Secure Key (ISK), a new processor technology that uses a local entropy source to improve random number generation that has heretofore been used to improve cryptography. The results from this simulator indicate that only ∼5% of radio-flaring UCDs within the local interstellar neighborhood (<25 pc away) have been discovered. I discuss a number of scenarios that may explain this radio-flaring fraction and suggest that the observed behavior is likely a result of several factors. The performance of ISK as compared to other pseudorandom number generators is also evaluated, and its potential utility for other astrophysical codes is briefly described.

  9. Well-observed dynamics of flaring and peripheral coronal magnetic loops during an M-class limb flare

    International Nuclear Information System (INIS)

    Shen, Jinhua; Zhou, Tuanhui; Ji, Haisheng; Feng, Li; Wiegelmann, Thomas; Inhester, Bernd

    2014-01-01

    In this paper, we present a variety of well-observed dynamic behaviors for the flaring and peripheral magnetic loops of the M6.6 class extreme limb flare that occurred on 2011 February 24 (SOL2011-02-24T07:20) from EUV observations by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory and X-ray observations by RHESSI. The flaring loop motion confirms the earlier contraction-expansion picture. We find that the U-shaped trajectory delineated by the X-ray corona source of the flare roughly follows the direction of a filament eruption associated with the flare. Different temperature structures of the coronal source during the contraction and expansion phases strongly suggest different kinds of magnetic reconnection processes. For some peripheral loops, we discover that their dynamics are closely correlated with the filament eruption. During the slow rising to abrupt, fast rising of the filament, overlying peripheral magnetic loops display different responses. Two magnetic loops on the elbow of the active region had a slow descending motion followed by an abrupt successive fast contraction, while magnetic loops on the top of the filament were pushed outward, slowly being inflated for a while and then erupting as a moving front. We show that the filament activation and eruption play a dominant role in determining the dynamics of the overlying peripheral coronal magnetic loops.

  10. Instant CloudFlare starter

    CERN Document Server

    Dickey, Jeff

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. Written as a practical guide, CloudFlare Starter will show you all you need to know in order to effectively improve your online presence in a multitude of different ways. ""Instant CloudFlare Starter"" is a practical yet accessible guide for website owners looking to optimize their site for optimum security and maximum performance.

  11. Self-similar Lagrangian hydrodynamics of beam-heated solar flare atmospheres

    International Nuclear Information System (INIS)

    Brown, J.C.; Emslie, A.G.

    1989-01-01

    The one-dimensional hydrodynamic problem in Lagrangian coordinates (Y, t) is considered for which the specific energy input Q has a power-law dependence on both Y and t, and the initial density distribution is rho(0) which is directly proportional to Y exp gamma. In regimes where the contributions of radiation, conduction, quiescent heating, and gravitational terms in the energy equation are negligible compared to those arising from Q, the problem has a self-similar solution, with the hydrodynamic variables depending only on a single independent variable which is a combination of Y, t, and the dimensional constants of the problem. It is then shown that the problem of solar flare chromospheric heating due to collisional interaction of a beam of electrons (or protons) with a power-law energy spectrum can be approximated by such forms of Q(Y, t) and rho(0)(Y), and that other terms are negligible compared to Q over a restricted regime early in the flare. 29 refs

  12. Flare-related color effects in UV Ceti stars

    International Nuclear Information System (INIS)

    Flesch, T.R.

    1975-01-01

    The UV Ceti flare stars YZ CMi, BD+16 0 2708, EV Lac, and AD Leo were monitored photoelectrically for flare activity with the 76 centimeter reflecting telescope of the University of Florida's Rosemary Hill Observatory. Observations were carried out from January, 1973 to April, 1975. The instrumentation allowed simultaneous readings to be taken at 3500, 4632, and 6496A with a time resolution of 2 seconds. A total of 15 major events were observed, with 14 of these being observed in all three colors. All events showed the classical fast rise and slower decline that is typical of this type of activity. One event showed peculiar behavior in the red bandpass that may indicate strong dependence of the flare light in some cases on line emission. The data were applied to the fast electron model of flare activity proposed by Gurzadyan. Several serious inconsistencies in the theory were found that would not have been evident in single-channel monitoring. No event could be fitted in all three colors using consistent values of the unknown parameters in the theory. The most serious deficiencies in the theory were the wavelength dependence of the optical depth of the electron cloud and the lack of treatment of line emission behavior. Differential color indices for flare light are calculated and are shown to be essentially constant throughout the entire event for the stronger flares. A color-color plot of the flare light at maximum reveals that 11 of the flares show a linear relation. This relation indicates that the smaller the u-b index, the larger is the b-r index. This is probably directly involved with line emission during flare events. Future research possibilities are discussed, with spectroscopic studies and simultaneous multicolor observations being stressed

  13. Orbit of the OJ287 black hole binary as determined from the General Relativity centenary flare

    Science.gov (United States)

    Valtonen, Mauri; Gopakumar, Achamveedu; Mikkola, Seppo; Zola, Staszek; Ciprini, Stefano; Matsumoto, Katsura; Sadakane, Kozo; Kidger, Mark; Gazeas, Kosmas; Nilsson, Kari; Berdyugin, Andrei; Piirola, Vilppu; Jermak, Helen; Baliyan, Kiran; Hudec, Rene; Reichart, Daniel

    2016-05-01

    OJ287 goes through large optical flares twice each 12 years. The times of these flares have been predicted successfully now 5 times using a black hole binary model. In this model a secondary black hole goes around a primary black hole, impacting the accretion disk of the latter twice per orbital period, creating a thermal flare. Together with 6 flares from the historical data base, the set of flare timings determines uniquely the 7 parameters of the model: the two masses, the primary spin, the major axis, eccentricity and the phase of the orbit, plus a time delay parameter that gives the extent of time between accretion disk impacts and the related optical flares. Based on observations by the OJ287-15/16 Collaboration, OJ287 went into the phase of rapid flux rise on November 25, on the centenary of Einstein’s General Relativity, and peaked on December 5. At that time OJ287 was the brightest in over 30 years in optical wavelengths. The flare was of low polarization, and did not extend beyond the optical/UV region of the spectrum. On top of the main flare there were a number of small flares; their excess brightness correlates well with the simultaneous X-ray data. With these properties the main flare qualifies as the marker of the orbit of the secondary going around the primary black hole. Since the orbit solution is strongly over-determined, its parameters are known very accurately, at better than one percent level for the masses and the spin. The next flare is predicted to peak on July 28, 2019.Detailed monitoring of this event should allow us to test, for the first time, the celebrated black hole no-hair theorem for a massive black hole at the 10% level. The present data is consistent with the theorem only at a 30% level. The main difficulty in observing OJ287 from Earth at our predicted epoch is its closeness to the sun. Therefore, it is desirable to monitor OJ287 from a space-based telescope not in the vicinity of Earth. Unfortunately, this unique opportunity

  14. M DWARF FLARES FROM TIME-RESOLVED SLOAN DIGITAL SKY SURVEY SPECTRA

    International Nuclear Information System (INIS)

    Hilton, Eric J.; Hawley, Suzanne L.; Kowalski, Adam F.; West, Andrew A.

    2010-01-01

    We have identified 63 flares on M dwarfs from the individual component spectra in the Sloan Digital Sky Survey (SDSS) using a novel measurement of emission-line strength called the Flare Line Index. Each of the ∼38,000 M dwarfs in the SDSS low-mass star spectroscopic sample of West et al. was observed several times (usually 3-5) in exposures that were typically 9-25 minutes in duration. Our criteria allowed us to identify flares that exhibit very strong Hα and Hβ emission-line strength and/or significant variability in those lines throughout the course of the exposures. The flares we identified have characteristics consistent with flares observed by classical spectroscopic monitoring. The flare duty cycle for the objects in our sample is found to increase from 0.02% for early M dwarfs to 3% for late M dwarfs. We find that the flare duty cycle is larger in the population near the Galactic plane and that the flare stars are more spatially restricted than the magnetically active but non-flaring stars. This suggests that flare frequency may be related to stellar age (younger stars are more likely to flare) and that the flare stars are younger than the mean active population.

  15. Narrow-band radio flares from red dwarf stars

    Energy Technology Data Exchange (ETDEWEB)

    White, S.M.; Kundu, M.R.; Jackson, P.D.

    1986-12-01

    VLA observations of narrow-band behavior in 20 cm flares from two red dwarf stars, L726 - 8A and AD Leo, are reported. The flare on L726 - 8A was observed at 1415 and 1515 MHz; the flux and the evolution differed significantly at the two frequencies. The flare on AD Leo lasted for 2 hr at 1415 MHz but did not appear at 1515 MHz. The AD Leo flare appears to rule out a source drifting through the stellar corona and is unlikely to be due to plasma emission. In the cyclotron maser model the narrow-band behavior reflects the range of magnetic fields present within the source. The apparent constancy of this field for 2 hr is difficult to understand if magnetic reconnection is the source of energy for the flare. The consistent polarization exhibited by red dwarf flares at 20 cm may be related to stellar activity cycles, and changes in this polarization will permit measuring the length of these cycles. 22 references.

  16. Transient behavior of a flare-associated solar wind. I - Gas dynamics in a radial open field region

    Science.gov (United States)

    Nagai, F.

    1984-01-01

    A numerical investigation is conducted into the way in which a solar wind model initially satisfying both steady state and energy balance conditions is disturbed and deformed, under the assumption of heating that correspoonds to the energy release of solar flares of an importance value of approximately 1 which occur in radial open field regions. Flare-associated solar wind transient behavior is modeled for 1-8 solar radii. The coronal temperature around the heat source region rises, and a large thermal conductive flux flows inward to the chromosphere and outward to interplanetary space along field lines. The speed of the front of expanding chromospheric material generated by the impingement of the conduction front on the upper chromosphere exceeds the local sound velocity in a few minutes and eventually exceeds 100 million cm/sec.

  17. Radiating shocks and condensations in flares

    International Nuclear Information System (INIS)

    Fisher, G.H.

    1985-01-01

    Rapid energy release (by either ''thick target'' (beam) or ''thermal'' models of heating) in solar flare loop models usually leads to ''chromospheric evaporation,'' the process of heating cool chromospheric material to coronal temperatures, and the resulting increase in hot soft x-ray emitting plasma. The evaporated plasma flows up into the coronal portion of the loop because of the increased pressure in the evaporated region. However, the pressure increase also leads to a number of interesting phenomena in the flare chromosphere, which will be the subject of this paper. The sudden pressure increase in the evaporated plasma initiates a downward moving ''chromospheric condensation,'' an overdense region which gradually decelerates as it accretes material and propagates into the gravitationally stratified chromosphere. Solutions to an equation of motion for this condensation shows that its motion decays after about one minute of propagation into the chromosphere. When the front of this downflowing region is supersonic relative to the atmosphere ahead of it, a radiating shock will form. If the downflow is rapid enough, the shock strength should be sufficient to excite uv radiation normally associated with the transition region, and furthermore, the radiating shock will be brighter than the transition region. These results lead to a number of observationally testable relationships between the optical and ultraviolet spectra from the condensation and radiating shock

  18. Endodontic cellulitis 'flare-up'. Case report.

    Science.gov (United States)

    Matusow, R J

    1995-02-01

    Endodontic cellulitis involves facial swelling which can vary from mild to severe and can occur as a primary case or a flare-up following initial treatment of asymptomatic teeth with periapical lesions. The microbial spectrum in primary cases involves a significant mixture of anaerobic and facultative aerobic microbes, chiefly streptococci. In a previous study, cultures from flare-up cases, utilizing the same anaerobic techniques as in primary cases, revealed an absence of obligate anaerobes and an 80 per cent incidence of facultative aerobic streptococci. These cases also revealed a significant time lapse from onset of symptoms to the cellulitis phase. No sex or age factors were noted in the primary or flare-up cases. The purpose of this case report is to restate a traditional theory, namely, the alteration of the oxidation/reduction potential (Eh), as a major factor for endodontic cellulitis flare-ups; to confirm the pathogenic potential of oral facultative streptococci; and that asymptomatic endodontic lesions tend to exist with mixed aerobic/anaerobic microbial flora.

  19. ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Petrie, G. J. D.; Sudol, J. J.

    2010-01-01

    We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65 0 of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of ∼10 G to as high as ∼450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65 0 of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

  20. Distribution function of frequency of stellar flares in the Orion association

    International Nuclear Information System (INIS)

    Parsamyan, Eh.S.

    1980-01-01

    Using the chronology of discoveries of new flares and the chronology of confirmation i.e. the time distribution of second flares (Ambartsumian's method), the distribution function of frequency of flares on stars in the Orion association is obtained. A number of stars having different frequencies is also found. It is shown that flare stars with high flare frequency (ν -1 13sup(m). The quantities of flare stars in aggregates determined by two independent methods show that the number of flare stars in Orion association is about 1.5 times greater than in the Pleiades cluster [ru

  1. Brazil-Bolivia natural gas project challenges and solutions

    International Nuclear Information System (INIS)

    Costa, A.S.C.

    1993-01-01

    PETROBRAS, the Brazilian/International Integrated Oil and Gas Company, is leading US$ 4 billion natural gas project. The goal of this paper is to identify Project challenges and propose solutions. It starts with fundamentals. Natural gas' share in Brazilian primary energy demand is only 2%. Economic aspects and environmental concerns, however, are changing this picture. For the Bolivian economy to be linked to a relatively huge market, in the long-term, is certainly a suitable decision. Besides, this Project will promote regional integration, within and outside Marcosur economies. Reserves, market data and economics give support to a feasible Project Financial structure is the main challenge. INTERGAS, a new subsidiary of PETROBRAS is opened for 49% stock to private sector participation. As an integrated Project, many opportunities will be generated during construction and operation. E ampersand P, pipeline and downstream investments could bring different investors to different sectors

  2. A study on removal of elemental mercury in flue gas using fenton solution

    International Nuclear Information System (INIS)

    Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng; Zhang, Yongchun; Zhou, Jianfei; Zhang, Jun

    2015-01-01

    Highlights: • A novel technique on oxidation of Hg 0 using Fenton was proposed. • The effects of several process parameters on Hg 0 removal were studied. • Products and ·OH in solution were detected. • Reaction mechanism of Hg 0 removal was studied. • Simultaneous removal of Hg 0 , NO and SO 2 was also studied. - Abstract: A novel technique on oxidation-separation of elemental mercury (Hg 0 ) in flue gas using Fenton solution in a bubbling reactor was proposed. The effects of several process parameters (H 2 O 2 concentration, Hg 0 inlet concentration, Fe 2+ concentration, solution temperature, solution pH, gas flow) and several flue gas components (NO, SO 2 , O 2 , CO 2 , inorganic ions and particulate matters on Hg 0 removal were studied. The results indicate that H 2 O 2 concentration, Fe 2+ concentration, solution pH and gas flow have great effects on Hg 0 removal. Solution temperature, Hg 0 , NO, SO 2 , CO 3 2− and HCO 3 − concentrations also have significant effects on Hg 0 removal. However, Cl − , SO 4 2− , NO 3 − , O 2 and CO 2 concentrations only have slight effects on Hg 0 removal. Furthermore, reaction mechanism of Hg 0 removal and simultaneous removal process of Hg 0 , NO and SO 2 were also studied. Hg 0 is removed by oxidation of ·OH and oxidation of H 2 O 2 . The simultaneous removal efficiencies of 100% for SO 2 , 100% for Hg 0 and 88.3% for NO were obtained under optimal test conditions. The results demonstrated the feasibility of Hg 0 removal and simultaneous removal of Hg 0 , SO 2 and NO using Fenton solution in a bubbling reactor

  3. Endodontic flare-ups: a prospective study.

    Science.gov (United States)

    Alves, Vanessa de Oliveira

    2010-11-01

    The objective of this prospective clinical study was to evaluate the incidence of flare-ups (pain and/or swelling requiring endodontic interappointment and emergency treatment) and identify the risk factors associated with their occurrence in patients who received endodontic treatment from June 2006 to June 2007 at the endodontics clinic of the São Paulo Dental Association (APCD), Jardim Paulista branch, São Paulo, Brazil. The incidence of flare-ups was 1.71% out of 408 teeth that had received endodontic therapy. Statistical analysis using the chi-squared test (P flare-up rate and the presence of a periradicular radiolucency. Copyright © 2010 Mosby, Inc. All rights reserved.

  4. Multi-Period Natural Gas Market Modeling. Applications, Stochastic Extensions and Solution Approaches

    International Nuclear Information System (INIS)

    Egging, R.G.

    2010-11-01

    This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in

  5. A direct comparison of protein structure in the gas and solution phase: the Trp-cage

    DEFF Research Database (Denmark)

    Patriksson, Alexandra; Adams, Christopher M; Kjeldsen, Frank

    2007-01-01

    Molecular dynamics simulations of zwitterions of the Trp-cage protein in the gas phase show that the most stable ion in vacuo has preserved the charge locations acquired in solution. A direct comparison of the gas and solution-phase structures reveals that, despite the similarity in charge location...

  6. Flare Prediction Using Photospheric and Coronal Image Data

    Science.gov (United States)

    Jonas, E.; Shankar, V.; Bobra, M.; Recht, B.

    2016-12-01

    We attempt to forecast M-and X-class solar flares using a machine-learning algorithm and five years of image data from both the Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Assembly (AIA) instruments aboard the Solar Dynamics Observatory. HMI is the first instrument to continuously map the full-disk photospheric vector magnetic field from space (Schou et al., 2012). The AIA instrument maps the transition region and corona using various ultraviolet wavelengths (Lemen et al., 2012). HMI and AIA data are taken nearly simultaneously, providing an opportunity to study the entire solar atmosphere at a rapid cadence. Most flare forecasting efforts described in the literature use some parameterization of solar data - typically of the photospheric magnetic field within active regions. These numbers are considered to capture the information in any given image relevant to predicting solar flares. In our approach, we use HMI and AIA images of solar active regions and a deep convolutional kernel network to predict solar flares. This is effectively a series of shallow-but-wide random convolutional neural networks stacked and then trained with a large-scale block-weighted least squares solver. This algorithm automatically determines which patterns in the image data are most correlated with flaring activity and then uses these patterns to predict solar flares. Using the recently-developed KeystoneML machine learning framework, we construct a pipeline to process millions of images in a few hours on commodity cloud computing infrastructure. This is the first time vector magnetic field images have been combined with coronal imagery to forecast solar flares. This is also the first time such a large dataset of solar images, some 8.5 terabytes of images that together capture over 3000 active regions, has been used to forecast solar flares. We evaluate our method using various flare prediction windows defined in the literature (e.g. Ahmed et al., 2013) and a novel per

  7. Imaging Observations of Magnetic Reconnection in a Solar Eruptive Flare

    International Nuclear Information System (INIS)

    Li, Y.; Ding, M. D.; Sun, X.; Qiu, J.; Priest, E. R.

    2017-01-01

    Solar flares are among the most energetic events in the solar atmosphere. It is widely accepted that flares are powered by magnetic reconnection in the corona. An eruptive flare is usually accompanied by a coronal mass ejection, both of which are probably driven by the eruption of a magnetic flux rope (MFR). Here we report an eruptive flare on 2016 March 23 observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . The extreme-ultraviolet imaging observations exhibit the clear rise and eruption of an MFR. In particular, the observations reveal solid evidence of magnetic reconnection from both the corona and chromosphere during the flare. Moreover, weak reconnection is observed before the start of the flare. We find that the preflare weak reconnection is of tether-cutting type and helps the MFR to rise slowly. Induced by a further rise of the MFR, strong reconnection occurs in the rise phases of the flare, which is temporally related to the MFR eruption. We also find that the magnetic reconnection is more of 3D-type in the early phase, as manifested in a strong-to-weak shear transition in flare loops, and becomes more 2D-like in the later phase, as shown by the apparent rising motion of an arcade of flare loops.

  8. Imaging Observations of Magnetic Reconnection in a Solar Eruptive Flare

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.; Ding, M. D. [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China); Sun, X. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Qiu, J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Priest, E. R., E-mail: yingli@nju.edu.cn [School of Mathematics and Statistics, University of St Andrews, Fife KY16 9SS, Scotland (United Kingdom)

    2017-02-01

    Solar flares are among the most energetic events in the solar atmosphere. It is widely accepted that flares are powered by magnetic reconnection in the corona. An eruptive flare is usually accompanied by a coronal mass ejection, both of which are probably driven by the eruption of a magnetic flux rope (MFR). Here we report an eruptive flare on 2016 March 23 observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . The extreme-ultraviolet imaging observations exhibit the clear rise and eruption of an MFR. In particular, the observations reveal solid evidence of magnetic reconnection from both the corona and chromosphere during the flare. Moreover, weak reconnection is observed before the start of the flare. We find that the preflare weak reconnection is of tether-cutting type and helps the MFR to rise slowly. Induced by a further rise of the MFR, strong reconnection occurs in the rise phases of the flare, which is temporally related to the MFR eruption. We also find that the magnetic reconnection is more of 3D-type in the early phase, as manifested in a strong-to-weak shear transition in flare loops, and becomes more 2D-like in the later phase, as shown by the apparent rising motion of an arcade of flare loops.

  9. The Crab Nebula flaring activity

    Energy Technology Data Exchange (ETDEWEB)

    Montani, G., E-mail: giovanni.montani@frascati.enea.it [ENEA – C.R, UTFUS-MAG, via Enrico Fermi 45, I-00044 Frascati (RM) (Italy); Dipartimento di Fisica, Università di Roma “Sapienza”, p.le Aldo Moro 5, I-00185 Roma (Italy); Bernardini, M.G. [INAF – Osservatorio Astronomico di Brera, via Bianchi 46, I-23807 Merate (Italy)

    2014-12-12

    The discovery made by AGILE and Fermi of a short time scale flaring activity in the gamma-ray energy emission of the Crab Nebula is a puzzling and unexpected feature, challenging particle acceleration theory. In the present work we propose the shock-induced magnetic reconnection as a viable mechanism to explain the Crab flares. We postulate that the emitting region is located at ∼10{sup 15} cm from the central pulsar, well inside the termination shock, which is exactly the emitting region size as estimated by the overall duration of the phenomenon ∼1 day. We find that this location corresponds to the radial distance at which the shock-induced magnetic reconnection process is able to accelerate the electrons up to a Lorentz factor ∼10{sup 9}, as required by the spectral fit of the observed Crab flare spectrum. The main merit of the present analysis is to highlight the relation between the observational constraints to the flare emission and the radius at which the reconnection can trigger the required Lorentz factor. We also discuss different scenarios that can induce the reconnection. We conclude that the existence of a plasma instability affecting the wind itself as the Weibel instability is the privileged scenario in our framework.

  10. X-ray Emission Characteristics of Flares Associated with CMEs ...

    Indian Academy of Sciences (India)

    tics of solar flares and their relationship with the dynamics of CMEs have ... lation between X-ray peak intensity of the flares with linear speed as well ... shear angle (θ1, measured at the flare onset), the final shear angle (θ2, measured at the.

  11. X-ray Emission from Solar Flares

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Solar flares; X-ray detectors; X-ray line emission and continuum; break energy; microflares. Abstract. Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in ...

  12. Forum Notes: The 1999 environmental research and technology development forum for the upstream oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-02-04

    This conference provided an opportunity to exchange information on current research and development projects regarding the environment and the petroleum industry. In addition to summaries of the various sessions, the booklet also includes a list of registrants and poster session participants. The conference was divided into the following three sessions: (1) site remediation, site restoration and groundwater, (2) ecological health, cumulative effects and agriculture, and (3) flaring, odour and greenhouse gas emissions. The session on site remediation heard papers that dealt with feedback on existing projects including soil quality guidelines for crude oil in agricultural soils, hydrophobicity, assessment of phytoremediation as an in-situ technique for cleaning sites polluted by oil, remediation using wetlands, land application of bioremediated soils, and flare pit characterization. The session on ecological health was treated to presentations describing research and development projects including the Eastern Slopes Grizzly Bear Project, the Native Prairie Revegetation Project, and the Caroline Livestock Study. The session on flaring and greenhouse gas emissions described research and development projects on dehydrator benzene emissions, monitoring of odour causing compounds, flare speciation, flare performance, improved liquid separation, alternate technologies, improved measurement of methane fugitive emissions from gas operations, and methane emissions from heavy oil operations.

  13. Forum Notes: The 1999 environmental research and technology development forum for the upstream oil and gas industry

    International Nuclear Information System (INIS)

    1999-01-01

    This conference provided an opportunity to exchange information on current research and development projects regarding the environment and the petroleum industry. In addition to summaries of the various sessions, the booklet also includes a list of registrants and poster session participants. The conference was divided into the following three sessions: (1) site remediation, site restoration and groundwater, (2) ecological health, cumulative effects and agriculture, and (3) flaring, odour and greenhouse gas emissions. The session on site remediation heard papers that dealt with feedback on existing projects including soil quality guidelines for crude oil in agricultural soils, hydrophobicity, assessment of phytoremediation as an in-situ technique for cleaning sites polluted by oil, remediation using wetlands, land application of bioremediated soils, and flare pit characterization. The session on ecological health was treated to presentations describing research and development projects including the Eastern Slopes Grizzly Bear Project, the Native Prairie Revegetation Project, and the Caroline Livestock Study. The session on flaring and greenhouse gas emissions described research and development projects on dehydrator benzene emissions, monitoring of odour causing compounds, flare speciation, flare performance, improved liquid separation, alternate technologies, improved measurement of methane fugitive emissions from gas operations, and methane emissions from heavy oil operations

  14. HEATING OF FLARE LOOPS WITH OBSERVATIONALLY CONSTRAINED HEATING FUNCTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Jiong; Liu Wenjuan; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States)

    2012-06-20

    We analyze high-cadence high-resolution observations of a C3.2 flare obtained by AIA/SDO on 2010 August 1. The flare is a long-duration event with soft X-ray and EUV radiation lasting for over 4 hr. Analysis suggests that magnetic reconnection and formation of new loops continue for more than 2 hr. Furthermore, the UV 1600 Angstrom-Sign observations show that each of the individual pixels at the feet of flare loops is brightened instantaneously with a timescale of a few minutes, and decays over a much longer timescale of more than 30 minutes. We use these spatially resolved UV light curves during the rise phase to construct empirical heating functions for individual flare loops, and model heating of coronal plasmas in these loops. The total coronal radiation of these flare loops are compared with soft X-ray and EUV radiation fluxes measured by GOES and AIA. This study presents a method to observationally infer heating functions in numerous flare loops that are formed and heated sequentially by reconnection throughout the flare, and provides a very useful constraint to coronal heating models.

  15. THE FLARE-ONA OF EK DRACONIS

    International Nuclear Information System (INIS)

    Ayres, Thomas R.

    2015-01-01

    EK Draconis (HD 129333: G1.5 V) is a well-known young (50 Myr) solar analog. In 2012, Hubble Space Telescope returned to EK Dra to follow up a far-ultraviolet (FUV) SNAPshot visit by Cosmic Origins Spectrograph (COS) two years earlier. The brief SNAP pointing had found surprisingly redshifted, impulsively variable subcoronal “hot-line” emission of Si iv 1400 Å (T ∼ 8 × 10 4 K). Serendipitously, the 2012 follow-on program witnessed one of the largest FUV flares ever recorded on a sunlike star, which again displayed strong redshifts (downflows) of 30–40 km s −1 , even after compensating for small systematics in the COS velocity scales, uncovered through a cross-calibration by Space Telescope Imaging Spectrograph (STIS). The (now reduced, but still substantial) ∼10 km s −1 hot-line redshifts outside the flaring interval did not vary with rotational phase, so cannot be caused by “Doppler imaging” (bright surface patches near a receding limb). Density diagnostic O iv] 1400 Å multiplet line ratios of EK Dra suggest n e ∼ 10 11 cm −3 , an order of magnitude larger than in low-activity solar twin α Centauri A, but typical of densities inferred in large stellar soft X-ray events. The self-similar FUV hot-line profiles between the flare decay and the subsequent more quiet periods, and the unchanging but high densities, reinforce a long-standing idea that the coronae of hyperactive dwarfs are flaring all the time, in a scale-free way; a flare-ona if you will. In this picture, the subsonic hot-line downflows probably are a byproduct of the post-flare cooling process, something like “coronal rain” on the Sun. All in all, the new STIS/COS program documents a complex, energetic, dynamic outer atmosphere of the young sunlike star

  16. 40 CFR 63.987 - Flare requirements.

    Science.gov (United States)

    2010-07-01

    ... specified in paragraphs (b)(3)(i) through (iv) of this section. (i) Method 22 of appendix A of part 60 shall...) cross sectional area of the flare tip. (iv) Flare flame or pilot monitors, as applicable, shall be..., ultra-violet beam sensor, or infrared sensor) capable of continuously detecting that at least one pilot...

  17. Variation of the solar wind velocity following solar flares

    International Nuclear Information System (INIS)

    Huang, Y.; Lee, Y.

    1975-01-01

    By use of the superposed epoch method, changes in the solar wind velocity following solar flares have been investigated by using the solar wind velocity data obtained by Pioneer 6 and 7 and Vela 3, 4, and 5 satellites. A significant increase of the solar wind velocity has been found on the second day following importance 3 solar flares and on the third day following importance 2 solar flares. No significant increase of the solar wind velocity has been found for limb flares. (auth)

  18. XSST/TRC rocket observations of July 13, 1982 flare

    International Nuclear Information System (INIS)

    Foing, B.H.; Bonnet, R.M.; Dame, L.; Bruner, M.; Acton, L.W.

    1986-01-01

    The present analysis of UV filtergrams of the July 13, 1982 solar flare obtained by the XSST/TRC rocket experiments has used calibrated intensities of the flare components to directly estimate the Lyman-alpha line flux, C IV line flux, and excess 160-nm continuum temperature brighness over the underlying plage. The values obtained are small by comparison with other observed or calculated equivalent quantities from the Machado (1980) model of flare F1. The corresponding power required to heat up to the temperature minimum over the 1200 sq Mm area is found to be 3.6 x 10 to the 25th erg/sec for this small X-ray C6 flare, 7 min after the ground-based observed flare maximum. 13 references

  19. Energy storage and deposition in a solar flare

    Science.gov (United States)

    Vorpahl, J. A.

    1976-01-01

    X-ray pictures of a solar flare taken with the S-056 X-ray telescope aboard Skylab are interpreted in terms of flare energy deposition and storage. The close similarity between calculated magnetic-field lines and the overall structure of the X-ray core is shown to suggest that the flare occurred in an entire arcade of loops. It is found that different X-ray features brightened sequentially as the flare evolved, indicating that some triggering disturbance moved from one side to the other in the flare core. A propagation velocity of 180 to 280 km/s is computed, and it is proposed that the geometry of the loop arcade strongly influenced the propagation of the triggering disturbance as well as the storage and site of the subsequent energy deposition. Some possible physical causes for the sequential X-ray brightening are examined, and a magnetosonic wave is suggested as the triggering disturbance. 'Correct' conditions for energy release are considered

  20. Endodontic flare up: incidence and association of possible risk factors.

    Science.gov (United States)

    Gbadebo, S O; Sulaiman, A O; Anifowose, O O

    2016-06-01

    Endodontic emergency during root canal treatment (flare up) is a common occurrence in multivisit root canal treatment (RCT) and it may be associated with many factors. The occurrence however can affect the prognosis of the tooth and the patient -clinician relationship. To determine the incidence and risk factors associated with occurrence of flare up in a multi visit RCT. Patients planned for multi-visit (RCT) were recruited for the research. Standard protocol was followed in all cases. After the first visit, the patients were followed up for possible development of flare up. Patients' demographics, presence or absence of preoperative pain, status of the pulp and occurrence of flare up were among the data collected. Data was analyzed using SPSS version 20 with level of significance set at P flare up was 8.5%. Prior to treatment, 47% of the cases had pain, 61.3% had apical radioluscency and 83% had pulpal necrosis. Majority (7, 77.8%) of the flare up occurred after the first visit (p=0.000). Only pre- treatment pain had a statistical significant ielationship with occurrence of flare up (p=0.009). Incidence of flare up was 8.5% and the major risk factor was preoperative pain. First visit in a multi visit RCT is an important stage which if well handled, can reduce the incidence of flare up.

  1. Comparison of emission properties of two homologous flares in AR 11283

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yan; Jing, Ju; Wang, Shuo; Wang, Haimin, E-mail: yx2@njit.edu [Space Weather Research Lab, Center for Solar-Terrestrial Research, New Jersey Institute of Technology 323 Martin Luther King Boulevard, Newark, NJ 07102-1982 (United States)

    2014-05-20

    Large, complex, active regions may produce multiple flares within a certain period of one or two days. These flares could occur in the same location with similar morphologies, commonly referred to as 'homologous flares'. In 2011 September, active region NOAA 11283 produced a pair of homologous flares on the 6th and 7th, respectively. Both of them were white-light (WL) flares, as captured by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory in visible continuum at 6173 Å which is believed to originate from the deep solar atmosphere. We investigate the WL emission of these X-class flares with HMI's seeing-free imaging spectroscopy. The durations of impulsive peaks in the continuum are about 4 minutes. We compare the WL with hard X-ray (HXR) observations for the September 6 flare and find a good correlation between the continuum and HXR both spatially and temporally. In absence of RHESSI data during the second flare on September 7, the derivative of the GOES soft X-ray is used and also found to be well correlated temporally with the continuum. We measure the contrast enhancements, characteristic sizes, and HXR fluxes of the twin flares, which are similar for both flares, indicating analogous triggering and heating processes. However, the September 7 flare was associated with conspicuous sunquake signals whereas no seismic wave was detected during the flare on September 6. Therefore, this comparison suggests that the particle bombardment may not play a dominant role in producing the sunquake events studied in this paper.

  2. Prevalence of inter-appointment endodontic flare-ups and host-related factors.

    Science.gov (United States)

    Azim, Adham A; Azim, Katharina A; Abbott, Paul V

    2017-04-01

    The aims of this study were to report the prevalence of inter-appointment flare-ups following adequate root canal disinfection and to investigate the host factors contributing to its occurrence. One thousand five hundred patient records were reviewed and the prevalence of flare-up was recorded. Patients' root canal space status (vital, non-vital or retreatment), medical condition and demographics (age, gender, tooth type and position) were recorded from their dental records. Statistical analyses were performed to determine the impact of the recorded factors on flare-up occurrence. Nine hundred fifty-one patient records met the inclusion criteria. The prevalence of flare-up was 2.3 %. There was a correlation between the canal space status and patient's age with flare-up development (P flare-up occurrence and tooth type, location, gender or medical condition (P > 0.5). The root canal space status was the primary factor affecting flare-up occurrence. Patients >50 years had the highest risk in developing flare-ups. This article provides evidence that patients suffering from inflamed pulp will not develop flare-up if adequate cleaning and shaping of the root canal space was performed. It also shows that patients above the age of 50 are a high-risk group that is prone to flare-up development.

  3. Excitation of helium resonance lines in solar flares

    International Nuclear Information System (INIS)

    Porter, J.G.; Gebbie, K.B.; November, L.J.; Joint Institute for Laboratory Astrophysics, Boulder, CO; National Solar Observatory, Sunspot, NM)

    1985-01-01

    Helium resonance line intensities are calculated for a set of six flare models corresponding to two rates of heating and three widely varying incident fluxes of soft X-rays. The differing ionization and excitation equilibria produced by these models, the processes which dominate the various cases, and the predicted helium line spectra are examined. The line intensities and their ratios are compared with values derived from Skylab NRL spectroheliograms for a class M flare, thus determining which of these models most nearly represents the density vs temperature structure and soft X-ray flux in the flaring solar transition region, and the temperature and dominant mechanaism of formation of the helium line spectrum during a flare. 26 references

  4. Do Long-cadence Data of the Kepler Spacecraft Capture Basic Properties of Flares?

    Science.gov (United States)

    Yang, Huiqin; Liu, Jifeng; Qiao, Erlin; Zhang, Haotong; Gao, Qing; Cui, Kaiming; Han, Henggeng

    2018-06-01

    Flare research is becoming a burgeoning realm of interest in the study of stellar activity due to the launch of Kepler in 2009. Kepler provides data with two time resolutions, i.e., the long-cadence (LC) data with a time resolution of 30 minutes and the short-cadence (SC) data with a time resolution of 1 minute, both of which can be used to study stellar flares. In this paper, we search flares in light curves with both LC data and SC data, and compare them in aspects of the true-flare rate, the flare energy, the flare amplitude, and the flare duration. It is found that LC data systematically underestimated the energies of flares by 25%, and underestimated the amplitudes of flares by 60% compared with SC flares. The durations are systematically overestimated by 50% compared with SC flares. However, the above percentages are poorly constrained and there is a lot of scatter. About 60% of SC flares have not been detected by LC data. We investigate the limitation of LC data, and suggest that although LC data cannot reflect the detailed profiles of flares, they can also capture the basic properties of stellar flares.

  5. Frequent Flaring in the TRAPPIST-1 System—Unsuited for Life?

    Energy Technology Data Exchange (ETDEWEB)

    Vida, K.; Kővári, Zs.; Pál, A.; Oláh, K.; Kriskovics, L., E-mail: vidakris@konkoly.hu [Konkoly Observatory, MTA CSFK, H-1121 Budapest, Konkoly Thege M. út 15-17 (Hungary)

    2017-06-01

    We analyze the K2 light curve of the TRAPPIST-1 system. The Fourier analysis of the data suggests P {sub rot} = 3.295 ± 0.003 days. The light curve shows several flares, of which we analyzed 42 events with integrated flare energies of 1.26 × 10{sup 30}–1.24 × 10{sup 33} erg. Approximately 12% of the flares were complex, multi-peaked eruptions. The flaring and the possible rotational modulation shows no obvious correlation. The flaring activity of TRAPPIST-1 probably continuously alters the atmospheres of the orbiting exoplanets, which makes these less favorable for hosting life.

  6. Transport and containment of plasma, particles and energy within flares

    Science.gov (United States)

    Acton, L. W.; Brown, W. A.; Bruner, M. E. C.; Haisch, B. M.; Strong, K. T.

    1983-01-01

    Results from the analysis of flares observed by the Solar Maximum Mission (SMM) and a recent rocket experiment are discussed. Evidence for primary energy release in the corona through the interaction of magnetic structures, particle and plasma transport into more than a single magnetic structure at the time of a flare and a complex and changing magnetic topology during the course of a flare is found. The rocket data are examined for constraints on flare cooling, within the context of simple loop models. These results form a basis for comments on the limitations of simple loop models for flares.

  7. A model to estimate volume change due to radiolytic gas bubbles and thermal expansion in solution reactors

    International Nuclear Information System (INIS)

    Souto, F.J.; Heger, A.S.

    2001-01-01

    To investigate the effects of radiolytic gas bubbles and thermal expansion on the steady-state operation of solution reactors at the power level required for the production of medical isotopes, a calculational model has been developed. To validate this model, including its principal hypotheses, specific experiments at the Los Alamos National Laboratory SHEBA uranyl fluoride solution reactor were conducted. The following sections describe radiolytic gas generation in solution reactors, the equations to estimate the fuel solution volume change due to radiolytic gas bubbles and thermal expansion, the experiments conducted at SHEBA, and the comparison of experimental results and model calculations. (author)

  8. PRODUCTIVITY OF SOLAR FLARES AND MAGNETIC HELICITY INJECTION IN ACTIVE REGIONS

    International Nuclear Information System (INIS)

    Park, Sung-hong; Wang Haimin; Chae, Jongchul

    2010-01-01

    The main objective of this study is to better understand how magnetic helicity injection in an active region (AR) is related to the occurrence and intensity of solar flares. We therefore investigate the magnetic helicity injection rate and unsigned magnetic flux, as a reference. In total, 378 ARs are analyzed using SOHO/MDI magnetograms. The 24 hr averaged helicity injection rate and unsigned magnetic flux are compared with the flare index and the flare-productive probability in the next 24 hr following a measurement. In addition, we study the variation of helicity over a span of several days around the times of the 19 flares above M5.0 which occurred in selected strong flare-productive ARs. The major findings of this study are as follows: (1) for a sub-sample of 91 large ARs with unsigned magnetic fluxes in the range from (3-5) x 10 22 Mx, there is a difference in the magnetic helicity injection rate between flaring ARs and non-flaring ARs by a factor of 2; (2) the GOES C-flare-productive probability as a function of helicity injection displays a sharp boundary between flare-productive ARs and flare-quiet ones; (3) the history of helicity injection before all the 19 major flares displayed a common characteristic: a significant helicity accumulation of (3-45) x 10 42 Mx 2 during a phase of monotonically increasing helicity over 0.5-2 days. Our results support the notion that helicity injection is important in flares, but it is not effective to use it alone for the purpose of flare forecast. It is necessary to find a way to better characterize the time history of helicity injection as well as its spatial distribution inside ARs.

  9. Magnetohydrodynamic Simulations for Studying Solar Flare Trigger Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Muhamad, J.; Kusano, K.; Inoue, S.; Shiota, D. [Institute for Space-Earth Environmental Research, Nagoya University, Furocho, Chikusa-ku, Nagoya, Aichi, 464-8601 (Japan)

    2017-06-20

    In order to understand the flare trigger mechanism, we conduct three-dimensional magnetohydrodynamic simulations using a coronal magnetic field model derived from data observed by the Hinode satellite. Several types of magnetic bipoles are imposed into the photospheric boundary of the Nonlinear Force-free Field model of Active Region (AR) NOAA 10930 on 2006 December 13, to investigate what kind of magnetic disturbance may trigger the flare. As a result, we confirm that certain small bipole fields, which emerge into the highly sheared global magnetic field of an AR, can effectively trigger a flare. These bipole fields can be classified into two groups based on their orientation relative to the polarity inversion line: the so-called opposite polarity, and reversed shear structures, as suggested by Kusano et al. We also investigate the structure of the footpoints of reconnected field lines. By comparing the distribution of reconstructed field lines and observed flare ribbons, the trigger structure of the flare can be inferred. Our simulation suggests that the data-constrained simulation, taking into account both the large-scale magnetic structure and small-scale magnetic disturbance (such as emerging fluxes), is a good way to discover a flare-producing AR, which can be applied to space weather prediction.

  10. Debunking the myths: Natural gas and SO2 allowance solutions

    International Nuclear Information System (INIS)

    Roberts, G.D. Jr.

    1993-01-01

    During the decade of the 1990's and beyond, natural gas is expected to be the fuel of choice for a significant portion of new generation capacity. Natural gas already enjoys a greater than 50% market share as a fuel source in the non-regulated cogeneration and Independent Power Producer market. With the new administration in Washington, increased environmental focus will likely increase the attractiveness of natural gas based capacity expansions. While these various issues may appear to contribute to making this decade, the decade for natural gas, there are a number of challenges that must be met if the natural gas and power generation industries are going to satisfy the ever increasing needs of the marketplace. These challenges include: (1) myths of natural gas supply availability, (2) transportation and operational coordination issues, (3) uncertainty of price and reliability, and (4) natural gas for NO x and SO 2 compliance. The author believes that these challenges are actively being met and that there are existing solutions already being offered and incorporated into contracts by natural gas suppliers. The focus of this paper is how electric utilities need to become comfortable with the new natural gas industry and how services can be structured to meet these challenges of serving the electric market requirements

  11. New flare stars in the Pleiade. 3

    International Nuclear Information System (INIS)

    Parsamyan, Eh.S.

    1976-01-01

    The flare stars in the Pleiads were investigated. The observations were carried out from the second part of 1972 to the beginning of 1973. Data on 9 new and 9 repeat flares are given. The new data are compared with those obtained previously

  12. ON THE NON-KOLMOGOROV NATURE OF FLARE-PRODUCTIVE SOLAR ACTIVE REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mandage, Revati S. [Physics and Astronomy Department, Rice University, 6100 Main MS-61, Houston, TX 77005-1827 (United States); McAteer, R. T. James, E-mail: mcateer@nmsu.edu [Department of Astronomy, New Mexico State University, MSC 4500, Las Cruces, NM 88001 (United States)

    2016-12-20

    A magnetic power spectral analysis is performed on 53 solar active regions, observed from 2011 August to 2012 July. Magnetic field data obtained from the Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used to study the evolution of the magnetic power index as each region rotates across the solar disk. Active regions are classified based on the numbers and sizes of solar flares they produce in order to study the relationship between flare productivity and the magnetic power index. The choice of window size and inertial range plays a key role in determining the correct magnetic power index. The overall distribution of magnetic power indices has a range of 1.0–2.5. Flare-quiet regions peak at a value of 1.6. However, flare-productive regions peak at a value of 2.2. Overall, the histogram of the distribution of power indices of flare-productive active regions is well separated from flare-quiet active regions. Only 12% of flare-quiet regions exhibit an index greater than 2, whereas 90% of flare-productive regions exhibit an index greater than 2. Flare-quiet regions exhibit a high temporal variance (i.e., the index fluctuates between high and low values), whereas flare-productive regions maintain an index greater than 2 for several days. This shows the importance of including the temporal evolution of active regions in flare prediction studies, and highlights the potential of a 2–3 day prediction window for space weather applications.

  13. 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)

  14. Gamma-ray flares from the Crab Nebula.

    Science.gov (United States)

    Abdo, A A; Ackermann, M; Ajello, M; Allafort, A; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Cannon, A; Caraveo, P A; Casandjian, J M; Çelik, Ö; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Costamante, L; Cutini, S; D'Ammando, F; Dermer, C D; de Angelis, A; de Luca, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Dubois, R; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashi, K; Hayashida, M; Hays, E; Horan, D; Itoh, R; Jóhannesson, G; Johnson, A S; Johnson, T J; Khangulyan, D; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Longo, F; Loparco, F; Lubrano, P; Madejski, G M; Makeev, A; Marelli, M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Ormes, J F; Ozaki, M; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Pierbattista, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Sadrozinski, H F-W; Sanchez, D; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, P D; Spandre, G; Spinelli, P; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Wang, P; Wood, K S; Yang, Z; Ziegler, M

    2011-02-11

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 × 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.

  15. Gamma-ray flares from the Crab nebula

    International Nuclear Information System (INIS)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Casandjian, J.M.; Grenier, I.A.; Naumann-Godo, M.; Pierbattista, M.; Tibaldo, L.

    2011-01-01

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10 15 electron volts) electrons in a region smaller than 1.4 * 10 -2 parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory. (authors)

  16. Multi-period natural gas market modeling Applications, stochastic extensions and solution approaches

    Science.gov (United States)

    Egging, Rudolf Gerardus

    This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. 1 The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in

  17. An unorthodox X-Class Long-Duration Confined Flare

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Gou, Tingyu; Wang, Yuming; Liu, Kai [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China); Titov, Viacheslav S. [Predictive Science, Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Wang, Haimin, E-mail: rliu@ustc.edu.cn [Space Weather Research Laboratory, Center for Solar-Terrestrial Research, NJIT, Newark, NJ 07102 (United States)

    2014-07-20

    We report the observation of an X-class long-duration flare which is clearly confined. It appears as a compact-loop flare in the traditional EUV passbands (171 and 195 Å), but in the passbands sensitive to flare plasmas (94 and 131 Å), it exhibits a cusp-shaped structure above an arcade of loops like other long-duration events. Inspecting images in a running difference approach, we find that the seemingly diffuse, quasi-static cusp-shaped structure consists of multiple nested loops that repeatedly rise upward and disappear approaching the cusp edge. Over the gradual phase, we detect numerous episodes of loop rising, each lasting minutes. A differential emission measure analysis reveals that the temperature is highest at the top of the arcade and becomes cooler at higher altitudes within the cusp-shaped structure, contrary to typical long-duration flares. With a nonlinear force-free model, our analysis shows that the event mainly involves two adjacent sheared arcades separated by a T-type hyperbolic flux tube (HFT). One of the arcades harbors a magnetic flux rope, which is identified with a filament that survives the flare owing to the strong confining field. We conclude that a new emergence of magnetic flux in the other arcade triggers the flare, while the preexisting HFT and flux rope dictate the structure and dynamics of the flare loops and ribbons during the long-lasting decay phase, and that a quasi-separatrix layer high above the HFT could account for the cusp-shaped structure.

  18. NEW SOLAR EXTREME-ULTRAVIOLET IRRADIANCE OBSERVATIONS DURING FLARES

    International Nuclear Information System (INIS)

    Woods, Thomas N.; Hock, Rachel; Eparvier, Frank; Jones, Andrew R.; Chamberlin, Phillip C.; Klimchuk, James A.; Didkovsky, Leonid; Judge, Darrell; Mariska, John; Warren, Harry; Schrijver, Carolus J.; Webb, David F.; Bailey, Scott; Tobiska, W. Kent

    2011-01-01

    New solar extreme-ultraviolet (EUV) irradiance observations from the NASA Solar Dynamics Observatory (SDO) EUV Variability Experiment provide full coverage in the EUV range from 0.1 to 106 nm and continuously at a cadence of 10 s for spectra at 0.1 nm resolution and even faster, 0.25 s, for six EUV bands. These observations can be decomposed into four distinct characteristics during flares. First, the emissions that dominate during the flare's impulsive phase are the transition region emissions, such as the He II 30.4 nm. Second, the hot coronal emissions above 5 MK dominate during the gradual phase and are highly correlated with the GOES X-ray. A third flare characteristic in the EUV is coronal dimming, seen best in the cool corona, such as the Fe IX 17.1 nm. As the post-flare loops reconnect and cool, many of the EUV coronal emissions peak a few minutes after the GOES X-ray peak. One interesting variation of the post-eruptive loop reconnection is that warm coronal emissions (e.g., Fe XVI 33.5 nm) sometimes exhibit a second large peak separated from the primary flare event by many minutes to hours, with EUV emission originating not from the original flare site and its immediate vicinity, but rather from a volume of higher loops. We refer to this second peak as the EUV late phase. The characterization of many flares during the SDO mission is provided, including quantification of the spectral irradiance from the EUV late phase that cannot be inferred from GOES X-ray diagnostics.

  19. An essay on sunspots and solar flares

    International Nuclear Information System (INIS)

    Akasofu, S.-I.

    1984-01-01

    The presently prevailing theories of sunspots and solar flares rely on the hypothetical presence of magnetic flux tubes beneath the photosphere and the two subsequent hypotheses, their emergence above the photosphere and explosive magnetic reconnection, converting magnetic energy carried by the flux tubes for solar flare energy. In this paper, attention is paid to the fact that there are large-scale magnetic fields which divide the photosphere into positive and negative (line-of-sight) polarity regions and that they are likely to be more fundamental than sunspot fields, as emphasized most recently by McIntosh. A new phenomenological model of the sunspot pair formation is then constructed by considering an amplification process of these large-scale fields near their boundaries by shear flows, including localized vortex motions. The amplification results from a dynamo process associated with such vortex flows and the associated convergence flow in the large-scale fields. This dynamo process generates also some of the familiar ''force-free'' fields or the ''sheared'' magnetic fields in which the magnetic field-aligned currents are essential. Upward field-aligned currents generated by the dynamo process are carried by downward streaming electrons which are expected to be accelerated by an electric potential structure; a similar structure is responsible for accelerating auroral electrons in the magnetosphere. Depending on the magnetic field configuration and the shear flows, the current-carrying electrons precipitate into different geometrical patterns, causing circular flares, umbral flares, two-ribbon flares, etc. Thus, it is suggested that ''low temperature flares'' are directly driven by the photospheric dynamo process. (author)

  20. Developing a Construct to Evaluate Flares in Rheumatoid Arthritis: A Conceptual Report of the OMERACT RA Flare Definition Working Group

    DEFF Research Database (Denmark)

    Alten, Rieke; Choy, Ernest H; Christensen, Robin

    2011-01-01

    Rheumatoid arthritis (RA) patients and healthcare professionals (HCP) recognize that episodic worsening disease activity, often described as a "flare," is a common feature of RA that can contribute to impaired function and disability. However, there is no standard definition to enable measurement...... of its intensity and impact. The conceptual framework of the Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA Flare Definition Working Group includes an anchoring statement, developed at OMERACT 9 in 2008: "flare in RA" is defined as worsening of signs and symptoms of sufficient intensity....... The conceptual framework of flare takes into account validated approaches to measurement in RA: (1) various disease activity indices (e.g., Disease Activity Score, Clinical Disease Activity Index, Simplified Disease Activity Index); (2) use of patient-reported outcomes (PRO); and (3) characterization...

  1. Incidence of Endodontic Flare-ups and Its Related Factors: A Retrospective Study.

    Science.gov (United States)

    Nair, Manuja; Rahul, J; Devadathan, A; Mathew, Josey

    2017-01-01

    The aim and objective of the study were to determine the incidence of flare-ups during endodontic treatment and to identify the risk factors associated with flare-ups. A total of 1725 patients who were treated during the time period of 2009-2014 by the same endodontist were reviewed. Incidence of flare-up, patients' age, gender, status of pulp, tooth position, number of roots, and treatment provided were taken from their dental records. Relationship between these factors and flare-ups was examined. Statistical analysis was done using Pearson Chi-square test and Fisher's exact test. A total of 2% incidence of endodontic flare-ups was seen out of 1725 cases. Patient's age, gender, and diagnosis had a significant effect on the development of flare-ups ( P flare-up incidence. Diagnosis plays an important role in predicting the incidence of flare-ups. Patients in the age group of 40-60 years had a higher risk of developing flare-ups. Women compared to men are more prone to flare-ups.

  2. Computer utilization for the solution of gas supply problems

    Energy Technology Data Exchange (ETDEWEB)

    Raleigh, J T; Brady, J R

    1968-01-01

    The computer programs in this paper have proven to be useful tools in the solution of gas supply problems. Some of the management type of applications are: (1) long range planning projects; (2) comparison of various proposed gas purchase contracts; (3) to assist with budget and operational planning; (4) to assist in making cost-of-servic and rate predictions; (5) to investigate the feasibility of processing plants at any point on the system; and (6) to assist dispatching in its daily operation for cost and quality control. Competition, not only from the gas industry, but also from other forms of energy, makes it imperative that quantitative and economic information with regard to that marketable resource be available under a variety of assumptions and alternatives. This information can best be made available in a timely manner by the use of the computer.

  3. X-ray observations of solar flares with the Einstein Observatory

    International Nuclear Information System (INIS)

    Schmitt, J.H.M.M.; Fink, H.; Harnden, F.R. Jr.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA)

    1987-01-01

    The first Einstein Observatory Imaging Proportional Counter (IPC) observations of solar flares are presented. These flares were detected in scattered X-ray light when the X-ray telescope was pointed at the sunlit earth. The propagation and scattering of solar X-rays in the earth's atmosphere are discussed in order to be able to deduce the solar X-ray flux incident on top of the atmosphere from scattered X-ray intensity measurements. After this correction, the scattered X-ray data are interpreted as full-disk observations of the sun obtained with the same instrumentation used for observations of flares on other stars. Employing the same data analysis and interpretation techniques, extremely good agreement is found between the physical flare parameters deduced from IPC observations and known properties of compact loop flares. This agreement demonstrates that flare observations with the IPC can reveal physical parameters such as temperature and density quite accurately in the solar case and therefore suggests that the interpretations of stellar X-ray flare observations are on a physically sound basis. 26 references

  4. A study on removal of elemental mercury in flue gas using fenton solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng [School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Zhang, Yongchun [Jiangsu Province Special Equipment Safety Supervision Inspection Institute (Branch of Wuxi), Wuxi 214000 (China); Zhou, Jianfei [School of Energy and Power Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Zhang, Jun [Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing 210096 (China)

    2015-07-15

    Highlights: • A novel technique on oxidation of Hg{sup 0} using Fenton was proposed. • The effects of several process parameters on Hg{sup 0} removal were studied. • Products and ·OH in solution were detected. • Reaction mechanism of Hg{sup 0} removal was studied. • Simultaneous removal of Hg{sup 0}, NO and SO{sub 2} was also studied. - Abstract: A novel technique on oxidation-separation of elemental mercury (Hg{sup 0}) in flue gas using Fenton solution in a bubbling reactor was proposed. The effects of several process parameters (H{sub 2}O{sub 2} concentration, Hg{sup 0} inlet concentration, Fe{sup 2+} concentration, solution temperature, solution pH, gas flow) and several flue gas components (NO, SO{sub 2}, O{sub 2}, CO{sub 2}, inorganic ions and particulate matters on Hg{sup 0} removal were studied. The results indicate that H{sub 2}O{sub 2} concentration, Fe{sup 2+} concentration, solution pH and gas flow have great effects on Hg{sup 0} removal. Solution temperature, Hg{sup 0}, NO, SO{sub 2}, CO{sub 3}{sup 2−} and HCO{sub 3}{sup −} concentrations also have significant effects on Hg{sup 0} removal. However, Cl{sup −}, SO{sub 4}{sup 2−}, NO{sub 3}{sup −}, O{sub 2} and CO{sub 2} concentrations only have slight effects on Hg{sup 0} removal. Furthermore, reaction mechanism of Hg{sup 0} removal and simultaneous removal process of Hg{sup 0}, NO and SO{sub 2} were also studied. Hg{sup 0} is removed by oxidation of ·OH and oxidation of H{sub 2}O{sub 2}. The simultaneous removal efficiencies of 100% for SO{sub 2}, 100% for Hg{sup 0} and 88.3% for NO were obtained under optimal test conditions. The results demonstrated the feasibility of Hg{sup 0} removal and simultaneous removal of Hg{sup 0}, SO{sub 2} and NO using Fenton solution in a bubbling reactor.

  5. Quasi-periodic Pulsations in the Most Powerful Solar Flare of Cycle 24

    Science.gov (United States)

    Kolotkov, Dmitrii Y.; Pugh, Chloe E.; Broomhall, Anne-Marie; Nakariakov, Valery M.

    2018-05-01

    Quasi-periodic pulsations (QPPs) are common in solar flares and are now regularly observed in stellar flares. We present the detection of two different types of QPP signals in the thermal emission light curves of the X9.3-class solar flare SOL2017-09-06T12:02, which is the most powerful flare of Cycle 24. The period of the shorter-period QPP drifts from about 12 to 25 s during the flare. The observed properties of this QPP are consistent with a sausage oscillation of a plasma loop in the flaring active region. The period of the longer-period QPP is about 4 to 5 minutes. Its properties are compatible with standing slow magnetoacoustic oscillations, which are often detected in coronal loops. For both QPP signals, other mechanisms such as repetitive reconnection cannot be ruled out, however. The studied solar flare has an energy in the realm of observed stellar flares, and the fact that there is evidence of a short-period QPP signal typical of solar flares along with a long-period QPP signal more typical of stellar flares suggests that the different ranges of QPP periods typically observed in solar and stellar flares is likely due to observational constraints, and that similar physical processes may be occurring in solar and stellar flares.

  6. Flare stars of the Orion Nebula - spectra of an outburst

    International Nuclear Information System (INIS)

    Carter, B.D.; O'Mara, B.J.; Ross, J.E.

    1988-01-01

    For the first time, detailed, time-resolved spectra of a flare event of an Orion cluster flare star are presented. These spectra, covering ∼ λλ3600-4600, were obtained by using the Anglo-Australian Telescope with a fibre coupler to simultaneously monitor 23 flare stars in the region of the Orion Nebula. The flare spectra reveal continuous emission which filled in the photospheric Ca I 4226 A absorption, and hydrogen Balmer, Ca II H and K, He I 4026 A and He I 4471 A line emission. Overall, the spectral behaviour indicates similarities to strong outbursts of the classical dMe flare stars. (author)

  7. WHY IS A FLARE-RICH ACTIVE REGION CME-POOR?

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lijuan; Wang, Yuming; Shen, Chenglong; Ye, Pinzhong; Liu, Rui; Chen, Jun; Zhang, Quanhao; Wang, S. [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Jingxiu, E-mail: ymwang@ustc.edu.cn, E-mail: ljliu@mail.ustc.edu.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2016-08-01

    Solar active regions (ARs) are the major sources of two of the most violent solar eruptions, namely flares and coronal mass ejections (CMEs). The largest AR in the past 24 years, NOAA AR 12192, which crossed the visible disk from 2014 October 17 to 30, unusually produced more than one hundred flares, including 32 M-class and 6 X-class ones, but only one small CME. Flares and CMEs are believed to be two phenomena in the same eruptive process. Why is such a flare-rich AR so CME-poor? We compared this AR with other four ARs; two were productive in both and two were inert. The investigation of the photospheric parameters based on the SDO /HMI vector magnetogram reveals that the flare-rich AR 12192, as with the other two productive ARs, has larger magnetic flux, current, and free magnetic energy than the two inert ARs but, in contrast to the two productive ARs, it has no strong, concentrated current helicity along both sides of the flaring neutral line, indicating the absence of a mature magnetic structure consisting of highly sheared or twisted field lines. Furthermore, the decay index above the AR 12192 is relatively low, showing strong constraint. These results suggest that productive ARs are always large and have enough current and free energy to power flares, but whether or not a flare is accompanied by a CME is seemingly related to (1) the presence of a mature sheared or twisted core field serving as the seed of the CME, or (2) a weak enough constraint of the overlying arcades.

  8. Microbial causes of endodontic flare-ups.

    Science.gov (United States)

    Siqueira, Jose F

    2003-07-01

    Inter-appointment flare-up is characterized by the development of pain, swelling or both, following endodontic intervention. The causative factors of flare-ups encompass mechanical, chemical and/or microbial injury to the pulp or periradicular tissues. Of these factors, microorganisms are arguably the major causative agents of flare-ups. Even though the host is usually unable to eliminate the root canal infection, mobilization and further concentration of defence components at the periradicular tissues impede spreading of infection, and a balance between microbial aggression and host defences is commonly achieved. There are some situations during endodontic therapy in which such a balance may be disrupted in favour of microbial aggression, and an acute periradicular inflammation can ensue. Situations include apical extrusion of infected debris, changes in the root canal microbiota and/or in environmental conditions caused by incomplete chemo-mechanical preparation, secondary intraradicular infections and perhaps the increase in the oxidation-reduction potential within the root canal favouring the overgrowth of the facultative bacteria. Based on these situations, preventive measures against infective flare-ups are proposed, including selection of instrumentation techniques that extrude lesser amounts of debris apically; completion of the chemo-mechanical procedures in a single visit; use of an antimicrobial intracanal medicament between appointments in the treatment of infected cases; not leaving teeth open for drainage and maintenance of the aseptic chain throughout endodontic treatment. Knowledge about the microbial causes of flare-ups and adoption of appropriate preventive measures can significantly reduce the incidence of this highly distressing and undesirable clinical phenomenon.

  9. Laser flare photometry in clinical practice

    Directory of Open Access Journals (Sweden)

    Yury S Astakhov

    2016-06-01

    Full Text Available Laser flare photometry (LFP is the only quantitative and objective method for the evaluation of aqueous flare. There are numerous opportunities to use LFP in clinical practice, and they are discussed in the paper. It is especially helpful in management of uveitis patients, because it allows estimating the correct diagnosis, managing the patient during the treatment with noninvasive method and predicting relapses and complications.

  10. Flare-ups in endodontics and their relationship to various medicaments.

    Science.gov (United States)

    Ehrmann, Ernest H; Messer, Harold H; Clark, Robert M

    2007-12-01

    The purpose of this research is to investigate the frequency of endodontic flare-ups using a visual analogue scale. Definitions of flare-ups vary widely as does their reported frequency. A flare-up was defined as an increase of 20 or more points on the visual analogue scale for a given tooth, within the periods of 4 h and 24 h after the initial treatment appointment. The data from a previous study were used to determine the incidence of flare-ups after using three modalities (Ledermix, calcium hydroxide and no medication) to manage patients presenting for relief of pain of endodontic origin. A statistical analysis showed that there were no significant differences in flare-up rates at both the 4-h and 24-h periods between the three modalities. Further research is required using the above definition of a flare-up and standardising treatment protocols.

  11. The solar-flare infrared continuum: observational techniques and upper limits

    International Nuclear Information System (INIS)

    Hudson, H.S.

    1975-01-01

    Exploratory observations at 20μ and 350 μ have determined detection thresholds for solar flares in these wavelengths. In the 20μ range solar atmospheric fluctuations (the 'temperature field') set the basic limits on flare detectability at approximately 5K; at 350μ the extinction in the Earth's atmosphere provides the basic limitation of approximately 30 K. These thresholds are low enough for the successful detection of several infrared-emitting components of large flares. Limited observing time and lack of solar activity have prevented observations of large flares up to the present, but the techniques promise to be extremely useful in the future. The upper limits obtained thus far, for subflares, indicate that the thickness of the Hα flare region does not exceed approximately 10 km. This result confirms the conclusion of Suemoto and Hiei (1959) regarding the small effective thickness of the Hα-emitting regions in solar flares. (Auth.)

  12. Discovery of decaHz flaring in SAX J1808.4-3658

    Directory of Open Access Journals (Sweden)

    Bult P.

    2014-01-01

    Full Text Available We report on the discovery of strong decaHz flaring in the early decay of two out of five outbursts of the accreting millisecond X-ray pulsar SAX J1808.4-3658. The decaHz flaring switches on and, after ~3 days, off again, on a time scale of 1-2 hours. When the flaring is present, the total 0.05-10 Hz variability has a fractional rms amplitude of 20 to 30 percent, well in excess of the 8 to 12 percent rms broad-band noise usually seen in power spectra of SAX J1808 in this frequency range. Coherent 401 Hz pulsations are seen throughout the observations in which the decaHz flaring is detected. We find that the absolute amplitude of the pulsations varies with the flux modulation of the decaHz flaring, indicating that the flaring is caused by an accretion rate modulation already present in the accretion flow prior to matter entering the accretion funnel. We suggest that the decaHz flaring is the result of the Spruit-Taam instability [1]. This instability arises when the inner accretion disk approaches co-rotation. The rotation of the stellar magnetosphere then acts as a propeller, suppressing accretion onto the neutron star. A matter reservoir forms in the inner accretion disk, which episodically empties onto the neutron star, causing flares at a decaHz timescale. A similar explanation was proposed earlier for 1 Hz flaring occurring late in three of five outbursts, mutually exclusive with the decaHz flaring. The 1 Hz flaring was observed at luminosities a factor 5 to 10 below where we see the decaHz flaring. That a different branch of the Spruit-Taam instability could also act at the much higher luminosity levels of the decaHz flaring had recently been predicted by D’Angelo & Spruit [2, 3]. We discuss these findings in the context of the parameters of the Spruit-Taam-d’Angelo model of the instability. If confirmed, after millisecond pulsations, 1 Hz and decaHz flaring would be another diagnostic of the presence of a magnetosphere in accreting low

  13. Spots and White Light Flares in an L Dwarf

    Science.gov (United States)

    2013-01-01

    Program GN-2012A-Q-37) GMOS spectrograph (Hook et al. 2004) when a series of flares occurred. A spectrum of the most powerful flare in its impulsive...10:14 Hα HeI HeI HeI OI Fig. 4. Gemini-North GMOS spectra of W1906+40 in quiescence (below) and in flare. Note the broad Hα, atomic emission lines

  14. The magnetic field of active region 11158 during the 2011 February 12-17 flares: Differences between photospheric extrapolation and coronal forward-fitting methods

    International Nuclear Information System (INIS)

    Aschwanden, Markus J.; Sun, Xudong; Liu, Yang

    2014-01-01

    We developed a coronal nonlinear force-free field (COR-NLFFF) forward-fitting code that fits an approximate nonlinear force-free field (NLFFF) solution to the observed geometry of automatically traced coronal loops. In contrast to photospheric NLFFF codes, which calculate a magnetic field solution from the constraints of the transverse photospheric field, this new code uses coronal constraints instead, and this way provides important information on systematic errors of each magnetic field calculation method, as well as on the non-force-freeness in the lower chromosphere. In this study we applied the COR-NLFFF code to NOAA Active Region 11158, during the time interval of 2011 February 12-17, which includes an X2.2 GOES-class flare plus 35 M- and C-class flares. We calculated the free magnetic energy with a 6 minute cadence over 5 days. We find good agreement between the two types of codes for the total nonpotential E N and potential energy E P but find up to a factor of 4 discrepancy in the free energy E free = E N – E P and up to a factor of 10 discrepancy in the decrease of the free energy ΔE free during flares. The coronal NLFFF code exhibits a larger time variability and yields a decrease of free energy during the flare that is sufficient to satisfy the flare energy budget, while the photospheric NLFFF code shows much less time variability and an order of magnitude less free-energy decrease during flares. The discrepancy may partly be due to the preprocessing of photospheric vector data but more likely is due to the non-force-freeness in the lower chromosphere. We conclude that the coronal field cannot be correctly calculated on the basis of photospheric data alone and requires additional information on coronal loop geometries.

  15. ANATOMY OF A SOLAR FLARE: MEASUREMENTS OF THE 2006 DECEMBER 14 X-CLASS FLARE WITH GONG, HINODE, AND RHESSI

    International Nuclear Information System (INIS)

    Matthews, S. A.; Zharkov, S.; Zharkova, V. V.

    2011-01-01

    Some of the most challenging observations to explain in the context of existing flare models are those related to the lower atmosphere and below the solar surface. Such observations, including changes in the photospheric magnetic field and seismic emission, indicate the poorly understood connections between energy release in the corona and its impact in the photosphere and the solar interior. Using data from Hinode, TRACE, RHESSI, and GONG we study the temporal and spatial evolution of the 2006 December 14 X-class flare in the chromosphere, photosphere, and the solar interior. We investigate the connections between the emission at various atmospheric depths, including acoustic signatures obtained by time-distance and holography methods from the GONG data. We report the horizontal displacements observed in the photosphere linked to the timing and locations of the acoustic signatures we believe to be associated with this flare, their vertical and horizontal displacement velocities, and their potential implications for current models of flare dynamics.

  16. TEMPORAL EVOLUTION OF CHROMOSPHERIC OSCILLATIONS IN FLARING REGIONS: A PILOT STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Monsue, T.; Stassun, K. G. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Hill, F., E-mail: teresa.monsue@vanderbilt.edu, E-mail: keivan.stassun@vanderbilt.edu, E-mail: hill@email.noao.edu [National Solar Observatory, Tucson, AZ 85719 (United States)

    2016-10-01

    We have analyzed H α intensity images obtained at a 1 minute cadence with the Global Oscillation Network Group (GONG) system to investigate the properties of oscillations in the 0–8 mHz frequency band at the location and time of strong M- and X-class flares. For each of three subregions within two flaring active regions, we extracted time series from multiple distinct positions, including the flare core and quieter surrounding areas. The time series were analyzed with a moving power-map analysis to examine power as a function of frequency and time. We find that, in the flare core of all three subregions, the low-frequency power (∼1–2 mHz) is substantially enhanced immediately prior to and after the flare, and that power at all frequencies up to 8 mHz is depleted at flare maximum. This depletion is both frequency- and time-dependent, which probably reflects the changing depths visible during the flare in the bandpass of the filter. These variations are not observed outside the flare cores. The depletion may indicate that acoustic energy is being converted into thermal energy at flare maximum, while the low-frequency enhancement may arise from an instability in the chromosphere and provide an early warning of the flare onset. Dark lanes of reduced wave power are also visible in the power maps, which may arise from the interaction of the acoustic waves and the magnetic field.

  17. Solar flare loops observations and interpretations

    CERN Document Server

    Huang, Guangli; Ji, Haisheng; Ning, Zongjun

    2018-01-01

    This book provides results of analysis of typical solar events, statistical analysis, the diagnostics of energetic electrons and magnetic field, as well as the global behavior of solar flaring loops such as their contraction and expansion. It pays particular attention to analyzing solar flare loops with microwave, hard X-ray, optical and EUV emissions, as well as the theories of their radiation, and electron acceleration/transport. The results concerning influence of the pitch-angle anisotropy of non-thermal electrons on their microwave and hard X-ray emissions, new spectral behaviors in X-ray and microwave bands, and results related to the contraction of flaring loops, are widely discussed in the literature of solar physics. The book is useful for graduate students and researchers in solar and space physics.

  18. MAGNETIC AND DYNAMICAL PHOTOSPHERIC DISTURBANCES OBSERVED DURING AN M3.2 SOLAR FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Kuckein, C. [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482, Potsdam (Germany); Collados, M.; Sainz, R. Manso, E-mail: ckuckein@aip.de [Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, E-38205, La Laguna, Tenerife (Spain)

    2015-02-01

    This Letter reports on a set of full-Stokes spectropolarimetric observations in the near-infrared He i 10830 Å spectral region covering the pre-flare, flare, and post-flare phases of an M3.2 class solar flare. The flare originated on 2013 May 17 and belonged to active region NOAA 11748. We detected strong He i 10830 Å emission in the flare. The red component of the He i triplet peaks at an intensity ratio to the continuum of about 1.86. During the flare, He i Stokes V is substantially larger and appears reversed compared to the usually larger Si i Stokes V profile. The photospheric Si i inversions of the four Stokes profiles reveal the following: (1) the magnetic field strength in the photosphere decreases or is even absent during the flare phase, as compared to the pre-flare phase. However, this decrease is not permanent. After the flare, the magnetic field recovers its pre-flare configuration in a short time (i.e., 30 minutes after the flare). (2) In the photosphere, the line of sight velocities show a regular granular up- and downflow pattern before the flare erupts. During the flare, upflows (blueshifts) dominate the area where the flare is produced. Evaporation rates of ∼10{sup −3} and ∼10{sup −4} g cm{sup −2} s{sup −1} have been derived in the deep and high photosphere, respectively, capable of increasing the chromospheric density by a factor of two in about 400 s.

  19. Forecasting Flare Activity Using Deep Convolutional Neural Networks

    Science.gov (United States)

    Hernandez, T.

    2017-12-01

    Current operational flare forecasting relies on human morphological analysis of active regions and the persistence of solar flare activity through time (i.e. that the Sun will continue to do what it is doing right now: flaring or remaining calm). In this talk we present the results of applying deep Convolutional Neural Networks (CNNs) to the problem of solar flare forecasting. CNNs operate by training a set of tunable spatial filters that, in combination with neural layer interconnectivity, allow CNNs to automatically identify significant spatial structures predictive for classification and regression problems. We will start by discussing the applicability and success rate of the approach, the advantages it has over non-automated forecasts, and how mining our trained neural network provides a fresh look into the mechanisms behind magnetic energy storage and release.

  20. Automated flare forecasting using a statistical learning technique

    Science.gov (United States)

    Yuan, Yuan; Shih, Frank Y.; Jing, Ju; Wang, Hai-Min

    2010-08-01

    We present a new method for automatically forecasting the occurrence of solar flares based on photospheric magnetic measurements. The method is a cascading combination of an ordinal logistic regression model and a support vector machine classifier. The predictive variables are three photospheric magnetic parameters, i.e., the total unsigned magnetic flux, length of the strong-gradient magnetic polarity inversion line, and total magnetic energy dissipation. The output is true or false for the occurrence of a certain level of flares within 24 hours. Experimental results, from a sample of 230 active regions between 1996 and 2005, show the accuracies of a 24-hour flare forecast to be 0.86, 0.72, 0.65 and 0.84 respectively for the four different levels. Comparison shows an improvement in the accuracy of X-class flare forecasting.

  1. Statistical and observational research of solar flare for total spectra and geometrical features

    Science.gov (United States)

    Nishimoto, S.; Watanabe, K.; Imada, S.; Kawate, T.; Lee, K. S.

    2017-12-01

    Impulsive energy release phenomena such as solar flares, sometimes affect to the solar-terrestrial environment. Usually, we use soft X-ray flux (GOES class) as the index of flare scale. However, the magnitude of effect to the solar-terrestrial environment is not proportional to that scale. To identify the relationship between solar flare phenomena and influence to the solar-terrestrial environment, we need to understand the full spectrum of solar flares. There is the solar flare irradiance model named the Flare Irradiance Spectral Model (FISM) (Chamberlin et al., 2006, 2007, 2008). The FISM can estimate solar flare spectra with high wavelength resolution. However, this model can not express the time evolution of emitted plasma during the solar flare, and has low accuracy on short wavelength that strongly effects and/or controls the total flare spectra. For the purpose of obtaining the time evolution of total solar flare spectra, we are performing statistical analysis of the electromagnetic data of solar flares. In this study, we select solar flare events larger than M-class from the Hinode flare catalogue (Watanabe et al., 2012). First, we focus on the EUV emission observed by the SDO/EVE. We examined the intensities and time evolutions of five EUV lines of 55 flare events. As a result, we found positive correlation between the "soft X-ray flux" and the "EUV peak flux" for all EVU lines. Moreover, we found that hot lines peaked earlier than cool lines of the EUV light curves. We also examined the hard X-ray data obtained by RHESSI. When we analyzed 163 events, we found good correlation between the "hard X-ray intensity" and the "soft X-ray flux". Because it seems that the geometrical features of solar flares effect to those time evolutions, we also looked into flare ribbons observed by SDO/AIA. We examined 21 flare events, and found positive correlation between the "GOES duration" and the "ribbon length". We also found positive correlation between the "ribbon

  2. SIZE DISTRIBUTIONS OF SOLAR FLARES AND SOLAR ENERGETIC PARTICLE EVENTS

    International Nuclear Information System (INIS)

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-01-01

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (≥1000 km s –1 ) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (α values) of power-law size distributions of the peak 1-8 Å fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes ≥1 pr cm –2 s –1 sr –1 ) and (b) fast CMEs were ∼1.3-1.4 compared to ∼1.2 for the peak proton fluxes of >10 MeV SEP events and ∼2 for the peak 1-8 Å fluxes of all SXR flares. The difference of ∼0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  3. HIGH RESOLUTION He i 10830 Å NARROW-BAND IMAGING OF AN M-CLASS FLARE. I. ANALYSIS OF SUNSPOT DYNAMICS DURING FLARING

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ya; Su, Yingna; Hong, Zhenxiang; Ji, Haisheng [Key Laboratory of DMSA, Purple Mountain Observatory, CAS, Nanjing, 210008 (China); Zeng, Zhicheng; Goode, Philip R.; Cao, Wenda [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Ji, Kaifan [Yunnan Astronomical Observatories, Kunming 650011 (China)

    2016-12-20

    In this paper, we report our first-step results of high resolution He i 10830 Å narrow-band imaging (bandpass: 0.5 Å) of an M1.8 class two-ribbon flare on 2012 July 5. The flare was observed with the 1.6 m aperture New Solar Telescope at Big Bear Solar Observatory. For this unique data set, sunspot dynamics during flaring were analyzed for the first time. By directly imaging the upper chromosphere, running penumbral waves are clearly seen as an outward extension of umbral flashes; both take the form of absorption in the 10830 Å narrow-band images. From a space–time image made of a slit cutting across a flare ribbon and the sunspot, we find that the dark lanes for umbral flashes and penumbral waves are obviously broadened after the flare. The most prominent feature is the sudden appearance of an oscillating absorption strip inside the ribbon when it sweeps into the sunspot’s penumbral and umbral regions. During each oscillation, outwardly propagating umbral flashes and subsequent penumbral waves rush out into the inwardly sweeping ribbon, followed by a return of the absorption strip with similar speed. We tentatively explain the phenomena as the result of a sudden increase in the density of ortho-helium atoms in the area of the sunspot being excited by the flare’s extreme ultraviolet illumination. This explanation is based on the observation that 10830 Å absorption around the sunspot area gets enhanced during the flare. Nevertheless, questions are still open and we need further well-devised observations to investigate the behavior of sunspot dynamics during flares.

  4. Flares of Orion population variables in the association Taurus T3

    International Nuclear Information System (INIS)

    Khodzhaev, A.S.; AN Armyanskoj SSR, Byurakan. Astrofizicheskaya Observatoriya)

    1987-01-01

    Thirteen new flare stars, proved to be irregular variables of Orion Population, were discovered from a study of the Taurus Dark Cloud region by the homogeneous photographic multipose method on the wide angle Schmidt telescopes of the Byurakan Astorphysical Observatory. Seventeen flares on these stars were detected for about 750 hours of the effective observing time. The analysis of the complicated light curves of these flares shows a great variety and multiplicity of this phenomenon and various dynamics of flare energy release processes. The existence of flare stars with some properties typical for both of the T Tauri and UV Ceti stars simulteneously indicates nonstable stars. The population of flare stars in the Taurus Dark Cloud region is apparently as young as in Orion and Monoceros

  5. Flare pit reclamation in British Columbia

    International Nuclear Information System (INIS)

    Mitchell, J.D.

    1997-01-01

    The legislative acts and policies administered by the Pollution Prevention program of the B.C. Ministry of Environment, Lands and Parks, (MELP) were reviewed. MELP is responsible for protecting land, water, air and living resources. Past oil and gas activities have left behind high levels of hazardous materials spills on the land which can pose a risk to human health. Flare pits are also a potential source of soil and groundwater contamination, therefore proper management and remediation of these sites is critical to ensuring that adverse impacts do not occur due to contamination of the sites. MELP has created a Contaminated Sites Regulation (CSR) which presents a consistent approach to ensuring protection of human health, the environment and property. This paper explores key provisions of the CSR, the prescribed contaminated sites management process and compares the B.C. legislation with that of neighbouring Alberta. 5 refs., 1 tab., 4 figs

  6. Some evidence on the evolution of the flare mechanism in dwarf stars

    Energy Technology Data Exchange (ETDEWEB)

    Skumanich, A.

    1986-10-01

    White-light flare parameters are estimated for the sun as a star. It is found that these parameters fall in the same domain as those for the dMe flare stars. In particular, it is found that the time-averaged flare power loss and quiescent coronal soft X-ray power loss at solar maximum satisfies the recently proposed flare power-coronal X-ray relation for dMe stars (Doyle and Butler; Skumanich). In addition, one finds that dM stars, which are believed to be magnetically evolved dMe stars, also satisfy the same relation. On this basis, an evolutionary scenario is suggested for the flare mechanism in which the total flare rate remains, more or less, constant but the mean flare yield decreases linearly with coronal X-ray strength. It is also suggested that the flare mechanism is universal in all magnetically active dwarfs. 48 references.

  7. Investigation of solar flares in X-ray and optical spectral region

    International Nuclear Information System (INIS)

    Kurt, V.; Kurochka, L.N.; Zenchenko, V.M.

    1989-01-01

    Measurements of hard X h radiation of 180 solar flares carried out on board of the space probes Venera-13,-14, were compared with measurements of optical and thermal X t radiation. Values of total energy release during a flare in these regions are calculated, and correlation analysis is carried out. The bond correlations found have shown that total energy of fast electrons, caused X h -flare in the flare pulse phase, and thermal energy at the end of a pulse phase are practically connected with each othesr functionally. Quantitative connection between a flare ball in H α -line and the most probable energy values, being in different radiation regions calculated in the scope of generally accepted models, is established. The total energy of an optical (cold) part of the flare, radiation energy in X-ray region and the energy introduced to the flare volume by energy particles are shown to be compared between each other

  8. Reduced combustion mechanism for C1-C4 hydrocarbons and its application in computational fluid dynamics flare modeling.

    Science.gov (United States)

    Damodara, Vijaya; Chen, Daniel H; Lou, Helen H; Rasel, Kader M A; Richmond, Peyton; Wang, Anan; Li, Xianchang

    2017-05-01

    Emissions from flares constitute unburned hydrocarbons, carbon monoxide (CO), soot, and other partially burned and altered hydrocarbons along with carbon dioxide (CO 2 ) and water. Soot or visible smoke is of particular concern for flare operators/regulatory agencies. The goal of the study is to develop a computational fluid dynamics (CFD) model capable of predicting flare combustion efficiency (CE) and soot emission. Since detailed combustion mechanisms are too complicated for (CFD) application, a 50-species reduced mechanism, LU 3.0.1, was developed. LU 3.0.1 is capable of handling C 4 hydrocarbons and soot precursor species (C 2 H 2 , C 2 H 4 , C 6 H 6 ). The new reduced mechanism LU 3.0.1 was first validated against experimental performance indicators: laminar flame speed, adiabatic flame temperature, and ignition delay. Further, CFD simulations using LU 3.0.1 were run to predict soot emission and CE of air-assisted flare tests conducted in 2010 in Tulsa, Oklahoma, using ANSYS Fluent software. Results of non-premixed probability density function (PDF) model and eddy dissipation concept (EDC) model are discussed. It is also noteworthy that when used in conjunction with the EDC turbulence-chemistry model, LU 3.0.1 can reasonably predict volatile organic compound (VOC) emissions as well. A reduced combustion mechanism containing 50 C 1 -C 4 species and soot precursors has been developed and validated against experimental data. The combustion mechanism is then employed in the computational fluid dynamics (CFD) of modeling of soot emission and combustion efficiency (CE) of controlled flares for which experimental soot and CE data are available. The validated CFD modeling tools are useful for oil, gas, and chemical industries to comply with U.S. Environmental Protection Agency's (EPA) mandate to achieve smokeless flaring with a high CE.

  9. A new technique in constructing closed-form solutions for nonlinear PDEs appearing in fluid mechanics and gas dynamics

    Directory of Open Access Journals (Sweden)

    Panayotounakos D. E.

    1996-01-01

    Full Text Available We develop a new unique technique in constructing closed-form solutions for several nonlinear partial differential systems appearing in fluid mechanics and gas dynamics. The obtained solutions include fewer arbitrary functions than needed for general solutions, fact that permits us to specify them according to the initial state, or the geometry, of each specific problem under consideration. In order to apply the before mentioned technique we construct closed-form solutions concerning the gas-dynamic equations with constant pressure, the dynamic equations of an ideal gas in isentropic flow, and the two-dimensional incompressible boundary layer flow.

  10. Critical Height of the Torus Instability in Two-ribbon Solar Flares

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dong; Liu, Rui; Wang, Yuming; Liu, Kai; Chen, Jun; Liu, Jiajia; Zhou, Zhenjun [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Min, E-mail: rliu@ustc.edu.cn [Department of Mathematics and Physics, Anhui Jianzhu University, Hefei 230601 (China)

    2017-07-01

    We studied the background field for 60 two-ribbon flares of M-and-above classes during 2011–2015. These flares are categorized into two groups, i.e., eruptive and confined flares, based on whether a flare is associated with a coronal mass ejection or not. The background field of source active regions is approximated by a potential field extrapolated from the B {sub z} component of vector magnetograms provided by the Helioseismic and Magnetic Imager. We calculated the decay index n of the background field above the flaring polarity inversion line, and defined a critical height h {sub crit} corresponding to the theoretical threshold ( n {sub crit} = 1.5) of the torus instability. We found that h {sub crit} is approximately half of the distance between the centroids of opposite polarities in active regions and that the distribution of h {sub crit} is bimodal: it is significantly higher for confined flares than for eruptive ones. The decay index increases monotonously with increasing height for 86% (84%) of the eruptive (confined) flares but displays a saddle-like profile for the rest, 14% (16%), which are found exclusively in active regions of multipolar field configuration. Moreover, n at the saddle bottom is significantly smaller in confined flares than that in eruptive ones. These results highlight the critical role of background field in regulating the eruptive behavior of two-ribbon flares.

  11. FLARE STARS—A FAVORABLE OBJECT FOR STUDYING MECHANISMS OF NONTHERMAL ASTROPHYSICAL PHENOMENA

    Energy Technology Data Exchange (ETDEWEB)

    Oks, E. [Physics Department, 206 Allison Lab., Auburn University, Auburn, AL 36849 (United States); Gershberg, R. E. [Crimean Astrophysical Observatory, Nauchny, Bakhchisaray region, Crimea, 298409 (Russian Federation)

    2016-03-01

    We present a spectroscopic method for diagnosing a low-frequency electrostatic plasma turbulence (LEPT) in plasmas of flare stars. This method had been previously developed by one of us and successfully applied to diagnosing the LEPT in solar flares. In distinction to our previous applications of the method, here we use the latest advances in the theory of the Stark broadening of hydrogen spectral lines. By analyzing observed emission Balmer lines, we show that it is very likely that the LEPT was developed in several flares of AD Leo, as well as in one flare of EV Lac. We found the LEPT (though of different field strengths) both in the explosive/impulsive phase and at the phase of the maximum, as well as at the gradual phase of the stellar flares. While for solar flares our method allows diagnosing the LEPT only in the most powerful flares, for the flare stars it seems that the method allows revealing the LEPT practically in every flare. It should be important to obtain new and better spectrograms of stellar flares, allowing their analysis by the method outlined in the present paper. This can be the most favorable way to the detailed understanding of the nature of nonthermal astrophysical phenomena.

  12. How is symptom flare defined in musculoskeletal conditions: A systematic review.

    Science.gov (United States)

    Costa, Nathalia; Ferreira, Manuela L; Cross, Marita; Makovey, Joanna; Hodges, Paul W

    2018-01-31

    To systematically review the definitions for "flare" in musculoskeletal conditions, the derivation processes, and validation of definitions for the 12 most burdensome musculoskeletal conditions. A literature search was conducted in MEDLINE, EMBASE, CINAHL, AMED, PsycInfo and Lilacs to identify studies that investigated derivation or validation of a flare definition, which we considered as a phrase or group of domains. Reports of derivation of flare definitions were identified for 9/12 musculoskeletal conditions. Validation of flare definitions was initiated for 4/12. For each condition, different derivation and validation methods have been used, with variable levels of consumer involvement, and in some cases different groups have worked on the process in parallel. Although some flare definitions began simply as "symptom worsening" or "change in treatment", most evolved into multidimensional definitions that include: pain, impact on function, joint symptoms, and emotional elements. Frequently initial attempts to create phrase to define the term flare evolved into consensus on the breadth of domains involved. Validation has compared flare definitions/domains against measures of disease activity, clinicians' diagnosis, response to drug therapy, or a combination. This review suggests that greater characterisation and definition of flares in musculoskeletal conditions are linked to the inclusion of multiple perspectives, multifaceted domains and compound comparators for their validation. Further work is required to optimise and test the derived definitions for most musculoskeletal conditions. As some elements are disease-specific, flare definitions cannot be extrapolated to other conditions. Research regarding flare in back pain (most burdensome disease) is limited. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Landfill gas-fired power plant pays cost of operating landfill

    International Nuclear Information System (INIS)

    Wallace, I.P.

    1991-01-01

    This paper reports on recovery of energy from refuse that has become increasingly attractive in the past decade. The continuing urbanization of our society has created major challenges in the disposal of our waste products. Because of public concern over the potential presence of toxins, and for other environmental reasons, management and regulation of active and inactive landfills have become much more stringent and costly. Palos Verdes landfill, owned jointly by the Los Angeles County Sanitation Districts and Los Angeles County, is located about three miles from the Pacific Ocean in the city of Rolling Hills Estates, Calif. The landfill was closed in 1980. The garbage was covered with six to eight feet of soil, and the area was landscaped. Part of this area has already been developed as the South Coast Botanical Gardens and Ernie Howlett Park. The remainder is scheduled to become a golf course. As refuse decays within a landfill, the natural anaerobic biological reaction generates a low-Btu methane gas along with carbon dioxide, known as landfill gas (LFG). The gas also contains other less desirable trace components generated by the decomposing garbage. Uncontrolled, these gases migrate to the surface and escape into the atmosphere where they generate environmental problems, including objectionable odors. The Sanitation Districts have installed a matrix of gas wells and a gas collection system to enable incineration of the gas in flares. This approach reduced aesthetic, environmental and safety concerns. However, emissions from the flares were still a problem. The Sanitation Districts then looked at alternatives to flaring the gas, one of which was electrical generation. Since the Sanitation Districts have no on-site use for thermal energy, power generation for use in the utility grid was deemed the most feasible alternative

  14. Radiation dose from solar flares at ground level

    International Nuclear Information System (INIS)

    O'Brien, K.

    1979-01-01

    Wdowczyk and Wolfendale (Nature, 268, 510, 1977) concluded that a very large solar flare producing exposure of 10 4 rad at ground level (lethal to almost any organism) has a possible frequency of once per 10 5 -10 8 yr. In the work reported similar results were obtained using a more elaborate model. Flares occuring from February 1956 to August 1972 were analyzed. The flare size distribution above the earth's atmosphere, and neutron flux, dose and dose equivalent at ground level at the latitude of Deep River, Canada, were calculated. The probable frequency of flares delivering various doses are given. Doses larger than 100 rad which have significant somatic effects on man and other animals may be delivered once in 10 6 years. The probability of 10 4 rad was found to be 10 -8 /yr. These calculations apply only to high geomagnetic latitudes. Field reversals during which the geomagnetic field is much weaker than current values total about 10% of the past 4 million years. This suggests that a very large flare delivering a large dose worldwide at ground level cannot be ruled out. (author)

  15. Ownership of solution and and evolved gas: Technical and legal perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, M. R. [Applied Reservoir Engineering and Evaluation (Canada); Friesen, J. G. [McCarthy Tetrault (Canada)

    1995-05-01

    A recent judgement of the Alberta Court of Appeal in `Prism Petroleum Ltd. et al vs. Omega Hydrocarbons Ltd.` affirmed earlier decisions, but failed to to resolve engineering issues such as terminology, PVT behaviour, producing mechanisms, the significance of an initial GOR, gas evolution in reservoirs, classification of oil and gas wells, concurrent production, enhanced recovery requirements, solution gas conservation and the effects of offset production. Some uncertainty also remained regarding the interpretation of the wording of the lease, responsibilities for costs of drilling, completion, surface facilities, operations where there has been a trespass, unjust enrichment, estoppel and limitation periods. The uncertainties regarding these legal and engineering concerns were addressed.

  16. Automated flare forecasting using a statistical learning technique

    International Nuclear Information System (INIS)

    Yuan Yuan; Shih, Frank Y.; Jing Ju; Wang Haimin

    2010-01-01

    We present a new method for automatically forecasting the occurrence of solar flares based on photospheric magnetic measurements. The method is a cascading combination of an ordinal logistic regression model and a support vector machine classifier. The predictive variables are three photospheric magnetic parameters, i.e., the total unsigned magnetic flux, length of the strong-gradient magnetic polarity inversion line, and total magnetic energy dissipation. The output is true or false for the occurrence of a certain level of flares within 24 hours. Experimental results, from a sample of 230 active regions between 1996 and 2005, show the accuracies of a 24-hour flare forecast to be 0.86, 0.72, 0.65 and 0.84 respectively for the four different levels. Comparison shows an improvement in the accuracy of X-class flare forecasting. (research papers)

  17. Gamma-ray Burst X-ray Flares Light Curve Fitting

    Science.gov (United States)

    Aubain, Jonisha

    2018-01-01

    Gamma Ray Bursts (GRBs) are the most luminous explosions in the Universe. These electromagnetic explosions produce jets demonstrated by a short burst of prompt gamma-ray emission followed by a broadband afterglow. There are sharp increases of flux in the X-ray light curves known as flares that occurs in about 50% of the afterglows. In this study, we characterized all of the X-ray afterglows that were detected by the Swift X-ray Telescope (XRT), whether with flares or without. We fit flares to the Norris function (Norris et al. 2005) and power laws with breaks where necessary (Racusin et al. 2009). After fitting the Norris function and power laws, we search for the residual pattern detected in prompt GRB pulses (Hakkila et al. 2014, 2015, 2017), that may indicate a common signature of shock physics. If we find the same signature in flares and prompt pulses, it provides insight into what causes them, as well as, how these flares are produced.

  18. Endodontic inter-appointment flare-ups: An example of chaos?

    Directory of Open Access Journals (Sweden)

    Poorya Jalali

    2015-01-01

    Full Text Available Introduction: Pain and/or swelling after instrumentation of a root canal constitute a significant complication during endodontic treatment. Despite a large number of articles discussing the causative factors behind endodontic flare-ups, the exact mechanism is still not understood. The Hypothesis: The seemingly irrational behavior of endodontic inter-appointment flare-ups may be due to sensitive dependence on initial conditions. A model based on Lorenz′ chaos theory is presented as a possible explanation for the sudden emergence and unpredictability of flare-ups. Evaluation of the Hypothesis: All studies agree on some common traits regarding inter-appointment flare-ups: Careful instrumentation can still cause flare-up; the host inflammatory response behaves as a complex nonlinear network; and also the poly-etiologic nature of this phenomenon all illustrate the sensitive dependence on initial conditions of the system. Integrating more variables (e.g., different species of bacteria into this already complex system will make it increasingly chaotic reflecting its unpredictable behavior.

  19. Multifractality as a Measure of Complexity in Solar Flare Activity

    Science.gov (United States)

    Sen, Asok K.

    2007-03-01

    In this paper we use the notion of multifractality to describe the complexity in H α flare activity during the solar cycles 21, 22, and 23. Both northern and southern hemisphere flare indices are analyzed. Multifractal behavior of the flare activity is characterized by calculating the singularity spectrum of the daily flare index time series in terms of the Hölder exponent. The broadness of the singularity spectrum gives a measure of the degree of multifractality or complexity in the flare index data. The broader the spectrum, the richer and more complex is the structure with a higher degree of multifractality. Using this broadness measure, complexity in the flare index data is compared between the northern and southern hemispheres in each of the three cycles, and among the three cycles in each of the two hemispheres. Other parameters of the singularity spectrum can also provide information about the fractal properties of the flare index data. For instance, an asymmetry to the left or right in the singularity spectrum indicates a dominance of high or low fractal exponents, respectively, reflecting a relative abundance of large or small fluctuations in the total energy emitted by the flares. Our results reveal that in the even (22nd) cycle the singularity spectra are very similar for the northern and southern hemispheres, whereas in the odd cycles (21st and 23rd) they differ significantly. In particular, we find that in cycle 21, the northern hemisphere flare index data have higher complexity than its southern counterpart, with an opposite pattern prevailing in cycle 23. Furthermore, small-scale fluctuations in the flare index time series are predominant in the northern hemisphere in the 21st cycle and are predominant in the southern hemisphere in the 23rd cycle. Based on these findings one might suggest that, from cycle to cycle, there exists a smooth switching between the northern and southern hemispheres in the multifractality of the flaring process. This new

  20. The Flare Irradiance Spectral Model (FISM) and its Contributions to Space Weather Research, the Flare Energy Budget, and Instrument Design

    Science.gov (United States)

    Chamberlin, Phillip

    2008-01-01

    The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution and on a 1-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric models. The seminar will begin with a brief overview of the FISM model, and also how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM. Some current studies will then be presented that use FISM estimations of the solar VUV irradiance to quantify the contributions of the increased irradiance from flares to Earth's increased thermospheric and ionospheric densites. Initial results will also be presented from a study looking at the electron density increases in the Martian atmosphere during a solar flare. Results will also be shown quantifying the VUV contributions to the total flare energy budget for both the impulsive and gradual phases of solar flares. Lastly, an example of how FISM can be used to simplify the design of future solar VUV irradiance instruments will be discussed, using the future NOAA GOES-R Extreme Ultraviolet and X-Ray Sensors (EXIS) space weather instrument.

  1. Variability in the Reporting of Serum Urate and Flares in Gout Clinical Trials

    DEFF Research Database (Denmark)

    Stamp, Lisa K; Morillon, Melanie B; Taylor, William J

    2018-01-01

    OBJECTIVE: To describe the ways in which serum urate (SU) and gout flares are reported in clinical trials, and to propose minimum reporting requirements. METHODS: This analysis was done as part of a systematic review aiming to validate SU as a biomarker for gout. The ways in which SU and flares.......3%) of these reporting at more than just the final study visit. Two ways of reporting gout flares were identified: mean flare rate and percentage of participants with flares. There was variability in time periods over which flares rates were reported. CONCLUSION: There is inconsistent reporting of SU and flares in gout...... studies. Reporting the percentage of participants who achieve a target SU reflects international treatment guidelines. SU should also be reported as a continuous variable with a relevant central and dispersion estimate. Gout flares should be reported as both percentage of participants and mean flare rates...

  2. DRAFTS: A DEEP, RAPID ARCHIVAL FLARE TRANSIENT SEARCH IN THE GALACTIC BULGE

    International Nuclear Information System (INIS)

    Osten, Rachel A.; Sahu, Kailash; Kowalski, Adam; Hawley, Suzanne L.

    2012-01-01

    We utilize the Sagittarius Window Eclipsing Extrasolar Planet Search Hubble Space Telescope/Advanced Camera for Surveys data set for a Deep Rapid Archival Flare Transient Search to constrain the flare rate toward the older stellar population in the Galactic bulge. During seven days of monitoring 229,293 stars brighter than V = 29.5, we find evidence for flaring activity in 105 stars between V = 20 and V = 28. We divided the sample into non-variable stars and variable stars whose light curves contain large-scale variability. The flare rate on variable stars is ∼700 times that of non-variable stars, with a significant correlation between the amount of underlying stellar variability and peak flare amplitude. The flare energy loss rates are generally higher than those of nearby well-studied single dMe flare stars. The distribution of proper motions is consistent with the flaring stars being at the distance and age of the Galactic bulge. If they are single dwarfs, then they span a range of ≈1.0-0.25 M ☉ . A majority of the flaring stars exhibit periodic photometric modulations with P < 3 days. If these are tidally locked magnetically active binary systems, then their fraction in the bulge is enhanced by a factor of ∼20 compared to the local value. These stars may be useful for placing constraints on the angular momentum evolution of cool close binary stars. Our results expand the type of stars studied for flares in the optical band, and suggest that future sensitive optical time-domain studies will have to contend with a larger sample of flaring stars than the M dwarf flare stars usually considered.

  3. [A clinical study of endodontic flare-ups].

    Science.gov (United States)

    Yeh, S J; Lin, Y T; Lu, S Y

    1994-06-01

    The purpose of this study was to investigate the clinical variables influencing endodontic flare-ups. Three hundred and thirteen teeth receiving endodontic treatment at the Endodontic Department, Chang Gung Memorial Hospital were studied from December 1992 to February 1993. Among them, 21 teeth with significant pain and 9 with apical swelling were noted after the first appointment of treatment. Three teeth with persistent pain and one with apical swelling were also found one week after completion of endodontic therapy. The results showed significant improvement of clinical symptoms and signs one week after completion of endodontic treatment in comparison with pretreatment and after the first appointment (p endodontic flare-ups after the first appointment of treatment (P endodontic flare-ups.

  4. Analytical Solution for Fractional Derivative Gas-Flow Equation in Porous Media

    KAUST Repository

    El-Amin, Mohamed; Radwan, Ahmed G.; Sun, Shuyu

    2017-01-01

    In this paper, we introduce an analytical solution of the fractional derivative gas transport equation using the power-series technique. We present a new universal transform, namely, generalized Boltzmann change of variable which depends on the fractional order, time and space. This universal transform is employed to transfer the partial differential equation into an ordinary differential equation. Moreover, the convergence of the solution has been investigated and found that solutions are unconditionally converged. Results are introduced and discussed for the universal variable and other physical parameters such as porosity and permeability of the reservoir; time and space.

  5. Analytical Solution for Fractional Derivative Gas-Flow Equation in Porous Media

    KAUST Repository

    El-Amin, Mohamed

    2017-07-06

    In this paper, we introduce an analytical solution of the fractional derivative gas transport equation using the power-series technique. We present a new universal transform, namely, generalized Boltzmann change of variable which depends on the fractional order, time and space. This universal transform is employed to transfer the partial differential equation into an ordinary differential equation. Moreover, the convergence of the solution has been investigated and found that solutions are unconditionally converged. Results are introduced and discussed for the universal variable and other physical parameters such as porosity and permeability of the reservoir; time and space.

  6. Studies of solar flares: Homology and X-ray line broadening

    Science.gov (United States)

    Ranns, Neale David Raymond

    This thesis starts with an introduction to the solar atmosphere and the physics that governs its behaviour. The formation processes of spectral lines are presented followed by an explanation of employed plasma diagnostic techniques and line broadening mechanisms. The current understanding on some principle concepts of flare physics are reviewed and the topics of flare homology and non-thermal line broadening are introduced. The many solar satellites and instrumentation that were utilised during this thesis are described. Analysis techniques for some instruments are also presented. A series of solar flares that conform to the literature definition for homologous flares are examined. The apparent homology is shown to be caused by emerging flux rather than continual stressing of a single, or group of, magnetic structure's. The implications for flare homology are discussed. The analysis of a solar flare with a rise and peak in the observed non-thermal X-ray line broadening (Vnt) is then performed. The location of the hot plasma within the flare area is determined and consequently the source of Vnt is located to be within and above the flare loops. The flare footpoints are therefore discarded as a possible source location. Viable source locations are discussed with a view to determining the dominant mechanism for the generation of line broadening. The timing relationships between the hard X-ray (HXR) flux and Vnt in many solar flares are then examined. I show that there is a causal relationship between these two parameters and that the HXR rise time is related to the time delay between the maxima of HXR flux and Vnt. The temporal evolution of Vnt is shown to be dependent upon the shape of the HXR burst. The implications of these results are discussed in terms of determining the line broadening mechanism and the limitations of the data. A summary of the results in this thesis is then presented together with suggestions for future research.

  7. Topics in High-Energy Astrophysics: X-ray Time Lags and Gamma-ray Flares

    Science.gov (United States)

    Kroon, John J.

    2016-03-01

    The Universe is host to a wide variety of high-energy processes that convert gravitational potential energy or rest-mass energy into non-thermal radiation such as bremsstrahlung and synchrotron. Prevailing models of X-ray emission from accreting Black Hole Binaries (BHBs) struggle to simultaneously fit the quiescent X-ray spectrum and the transients which result in the phenomenon known as X-ray time lags. And similarly, classical models of diffusive shock acceleration in pulsar wind nebulae fail to explain the extreme particle acceleration in very short timescales as is inferred from recent gamma-ray flares from the Crab nebula. In this dissertation, I develop new exact analytic models to shed light on these intriguing processes. I take a fresh look at the formation of X-ray time lags in compact sources using a new mathematical approach in which I obtain the exact Green's function solution. The resulting Green's function allows one to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. I obtain the exact solution for the dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous clouds. The model can successfully reproduce both the observed time lags and the quiescent X-ray spectrum using a single set of coronal parameters. I show that the implied coronal radii in the new model are significantly smaller than those obtained in the Monte Carlo simulations, hence greatly reducing the coronal heating problem. Recent bright gamma-ray flares from the Crab nebula observed by AGILE and Fermi reaching GeV energies and lasting several days challenge the contemporary model for particle acceleration in pulsar wind nebulae, specifically the diffusive shock acceleration model. Simulations indicate electron/positron pairs in the Crab nebula pulsar wind must be accelerated up to PeV energies in the presence of ambient magnetic fields with strength B ~100 microG. No

  8. Establishing a core domain set to measure rheumatoid arthritis flares

    DEFF Research Database (Denmark)

    Bykerk, Vivian P; Lie, Elisabeth; Bartlett, Susan J

    2014-01-01

    OBJECTIVE: The OMERACT Rheumatoid Arthritis (RA) Flare Group (FG) is developing a data-driven, patient-inclusive, consensus-based RA flare definition for use in clinical trials, longterm observational studies, and clinical practice. At OMERACT 11, we sought endorsement of a proposed core domain set...... to measure RA flare. METHODS: Patient and healthcare professional (HCP) qualitative studies, focus groups, and literature review, followed by patient and HCP Delphi exercises including combined Delphi consensus at Outcome Measures in Rheumatology 10 (OMERACT 10), identified potential domains to measure flare...... Filter 2.0 methodology. RESULTS: A pre-meeting combined Delphi exercise for defining flare identified 9 domains as important (>70% consensus from patients or HCP). Four new patient-reported domains beyond those included in the RA disease activity core set were proposed for inclusion (fatigue...

  9. PREDICTION OF SOLAR FLARES USING UNIQUE SIGNATURES OF MAGNETIC FIELD IMAGES

    Energy Technology Data Exchange (ETDEWEB)

    Raboonik, Abbas; Safari, Hossein; Alipour, Nasibe [Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of); Wheatland, Michael S., E-mail: raboonik@alumni.znu.ac.ir, E-mail: safari@znu.ac.ir [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

    2017-01-01

    Prediction of solar flares is an important task in solar physics. The occurrence of solar flares is highly dependent on the structure and topology of solar magnetic fields. A new method for predicting large (M- and X-class) flares is presented, which uses machine learning methods applied to the Zernike moments (ZM) of magnetograms observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory for a period of six years from 2010 June 2 to 2016 August 1. Magnetic field images consisting of the radial component of the magnetic field are converted to finite sets of ZMs and fed to the support vector machine classifier. ZMs have the capability to elicit unique features from any 2D image, which may allow more accurate classification. The results indicate whether an arbitrary active region has the potential to produce at least one large flare. We show that the majority of large flares can be predicted within 48 hr before their occurrence, with only 10 false negatives out of 385 flaring active region magnetograms and 21 false positives out of 179 non-flaring active region magnetograms. Our method may provide a useful tool for the prediction of solar flares, which can be employed alongside other forecasting methods.

  10. CONNECTING FLARES AND TRANSIENT MASS-LOSS EVENTS IN MAGNETICALLY ACTIVE STARS

    Energy Technology Data Exchange (ETDEWEB)

    Osten, Rachel A. [Space Telescope Science Institute 3700 San Martin Drive, Baltimore, MD 21218 (United States); Wolk, Scott J., E-mail: osten@stsci.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138 (United States)

    2015-08-10

    We explore the ramification of associating the energetics of extreme magnetic reconnection events with transient mass-loss in a stellar analogy with solar eruptive events. We establish energy partitions relative to the total bolometric radiated flare energy for different observed components of stellar flares and show that there is rough agreement for these values with solar flares. We apply an equipartition between the bolometric radiated flare energy and kinetic energy in an accompanying mass ejection, seen in solar eruptive events and expected from reconnection. This allows an integrated flare rate in a particular waveband to be used to estimate the amount of associated transient mass-loss. This approach is supported by a good correspondence between observational flare signatures on high flaring rate stars and the Sun, which suggests a common physical origin. If the frequent and extreme flares that young solar-like stars and low-mass stars experience are accompanied by transient mass-loss in the form of coronal mass ejections, then the cumulative effect of this mass-loss could be large. We find that for young solar-like stars and active M dwarfs, the total mass lost due to transient magnetic eruptions could have significant impacts on disk evolution, and thus planet formation, and also exoplanet habitability.

  11. Interplanetary medium and geomagnetic activity after compact flare triplets 1966-1981

    International Nuclear Information System (INIS)

    Ivanov, K.G.; Mikerina, N.V.; Pavlov, P.P.

    1986-01-01

    The interplanetary medium state and geomagnetic activity when the Earth is getting into this or that interplanetary disturbance zone after flare triplets, i.e. trains of three solar flares out of an active zone, are considered. There are the following conditionally differentiated zones in the interplanetary disturbance configuration: a forbidden (F), a perturbed (P) and a normal (N) zones of interplanetary disturbance. The interplanetary medium disturbances and geomagnetic activity after trains of three flares of class 2 and higher out of one of active zones depend on the following factors: the magnetic axis orientation of a bipolar group of active zone spots appeared after flares, time interval between the first and second flares in the train, flare intensity. The conditions of maximum disturbance occurrence pointed out. The interplanetary and geomagnetic disturbance intensity in the N zone is higher than that of the F and P zones (i.e. in the proximity of the great circle planes passing through the flares parallel with tha active zone magnetic axes), and it is higher after quasicompact rather than after compact triplets (i.e. it considerably grows when passing over the critical value of the time interval betwenn the first and second triplet flares, τ 12 =16 h)

  12. Flare Prediction Using Photospheric and Coronal Image Data

    Science.gov (United States)

    Jonas, Eric; Bobra, Monica; Shankar, Vaishaal; Todd Hoeksema, J.; Recht, Benjamin

    2018-03-01

    The precise physical process that triggers solar flares is not currently understood. Here we attempt to capture the signature of this mechanism in solar-image data of various wavelengths and use these signatures to predict flaring activity. We do this by developing an algorithm that i) automatically generates features in 5.5 TB of image data taken by the Solar Dynamics Observatory of the solar photosphere, chromosphere, transition region, and corona during the time period between May 2010 and May 2014, ii) combines these features with other features based on flaring history and a physical understanding of putative flaring processes, and iii) classifies these features to predict whether a solar active region will flare within a time period of T hours, where T = 2 and 24. Such an approach may be useful since, at the present time, there are no physical models of flares available for real-time prediction. We find that when optimizing for the True Skill Score (TSS), photospheric vector-magnetic-field data combined with flaring history yields the best performance, and when optimizing for the area under the precision-recall curve, all of the data are helpful. Our model performance yields a TSS of 0.84 ±0.03 and 0.81 ±0.03 in the T = 2- and 24-hour cases, respectively, and a value of 0.13 ±0.07 and 0.43 ±0.08 for the area under the precision-recall curve in the T=2- and 24-hour cases, respectively. These relatively high scores are competitive with previous attempts at solar prediction, but our different methodology and extreme care in task design and experimental setup provide an independent confirmation of these results. Given the similar values of algorithm performance across various types of models reported in the literature, we conclude that we can expect a certain baseline predictive capacity using these data. We believe that this is the first attempt to predict solar flares using photospheric vector-magnetic field data as well as multiple wavelengths of image

  13. Flare activity on UV CETI: visible and IUE observations

    International Nuclear Information System (INIS)

    Phillips, K.J.H.; Bromage, G.E.; Dufton, P.L.; Keenan, F.P.; Kingston, A.E.

    1988-06-01

    Simultaneous far-ultraviolet (IUE) spectroscopy and optical photometry and spectrophotometry of a flare on UV Ceti are reported. The flare reached ΔU = 2sup(m) but showed only modest enhancements in the IUE spectra. The optical spectrophotometry indicated broadened Balmer line profiles during the flare, with Hβ and Hγ clearly showing red wings. The results are compared with other IUE and optical observations of UV Ceti, and their solar analogues. (author)

  14. Search for correlation of neutrino events with solar flares in Kamiokande

    International Nuclear Information System (INIS)

    Hirata, K.S.; Kajita, T.; Kifune, T.

    1988-10-01

    A search has been made for a correlation between large solar flares and neutrino events observed in Kamiokande for the period of July 1983 - July 1988. No significant neutrino signal was found at the time of a solar flare, giving a limit on the time integrated 'solar-flare' ν e flux 7 (2.5 x 10 9 )/cm 2 per flare at 90 % confidence level, for E ν = 100 (50) MeV. These limits are 2000 (60) times smaller than the value required for neutrinos with those energies to account for the excess of signal in the 37 Cl solar neutrino experiment at some of the corresponding solar flare times. (author)

  15. Future flare compositions

    NARCIS (Netherlands)

    Lingen, J.L.N. van; Meuken, D.; Hackspik, M.M.; Mäkeläinen, T.; Weiser, V.; Poulson, G.W.

    2014-01-01

    This poster describes the work done within the Category B joint research project under the European Defence Agency (EDA) on Future Flare Compositions [1]. Contributing members were Finland, Germany, United Kingdom and the Netherlands. The program was aimed to identify the technology gaps that apply

  16. Some calculations using the two-dimensional turbulent combustion code flare

    International Nuclear Information System (INIS)

    Martin, D.

    1986-09-01

    A brief description of the code FLARE is given. Both the model used in FLARE and the numerical scheme used to implement the model are described. Results for the simulation of an experiment are presented and discussed. An alternative turbulence model to that used in FLARE is discussed but it is concluded that the original model is better. (author)

  17. Dynamics of flare sprays

    International Nuclear Information System (INIS)

    Tandberg-Hanssen, E.; Hansen, R.T.

    1980-01-01

    During solar cycle No. 20 new insight into the flare-spray phenomenon has been attained due to several innovations in solar optical-observing techniques (higher spatial resolution cinema-photography, tunable pass-band filters, multi-slit spectroscopy and extended angular field coronographs). From combined analysis of 13 well-observed sprays which occured between 1969-1974 we conclude that (i) the spray material originates from a preexisting active region filament which undergoes increased absorption some tens of minutes prior to the abrupt chromospheric brightening at the 'flare-start', and (ii) the spray material is confined within a steadily expanding, loop-shaped (presumably magnetically controlled) envelope with part of the material draining back down along one or both legs of the loop. (orig.)

  18. Methane flaring: an initiative in line with the greenhouse challenge

    International Nuclear Information System (INIS)

    Greenwood, D.

    1999-01-01

    Methane is a by-product of the coalification process. Once produced, it typically remains trapped within the coal seam and the surrounding strata. High quality black coals in Australia may contain up to 20 m 3 of methane per tonne of coal. In order to mine coal safely, this gas level must be reduced. Presence of gas at the coal face is a hazard as sparks created by coal extraction machine picks may ignite the gas/air mix. Concentrations of methane between approximately 5% and 15% in air create an explosive mixture. This represents a considerable potential safety risk for underground mining personnel. In Queensland, all underground mining personnel and equipment are protected by sensors that remove electrical power from machines should the ambient methane levels exceed 1.25%. While this assists in creating a safe working environment, it also halts coal production. Normal mine ventilation air removes a significant amount of methane, however in gassy mines the ventilation air flow required to maintain methane levels below the 1.25% limit can introduce other problems. These include excess airborne dust, which can lead to respiratory issues and poor visibility. A flare was installed at Central Colliery to achieve reduction of the greenhouse gas emissions. It would also be used to burn gas flow beyond that which can be effectively utilised by power generation

  19. Applying the Weighted Horizontal Magnetic Gradient Method to a Simulated Flaring Active Region

    Science.gov (United States)

    Korsós, M. B.; Chatterjee, P.; Erdélyi, R.

    2018-04-01

    Here, we test the weighted horizontal magnetic gradient (WG M ) as a flare precursor, introduced by Korsós et al., by applying it to a magnetohydrodynamic (MHD) simulation of solar-like flares. The preflare evolution of the WG M and the behavior of the distance parameter between the area-weighted barycenters of opposite-polarity sunspots at various heights is investigated in the simulated δ-type sunspot. Four flares emanated from this sunspot. We found the optimum heights above the photosphere where the flare precursors of the WG M method are identifiable prior to each flare. These optimum heights agree reasonably well with the heights of the occurrence of flares identified from the analysis of their thermal and ohmic heating signatures in the simulation. We also estimated the expected time of the flare onsets from the duration of the approaching–receding motion of the barycenters of opposite polarities before each single flare. The estimated onset time and the actual time of occurrence of each flare are in good agreement at the corresponding optimum heights. This numerical experiment further supports the use of flare precursors based on the WG M method.

  20. Flares in Biopsy-Proven Giant Cell Arteritis in Northern Italy

    Science.gov (United States)

    Restuccia, Giovanna; Boiardi, Luigi; Cavazza, Alberto; Catanoso, Mariagrazia; Macchioni, Pierluigi; Muratore, Francesco; Cimino, Luca; Aldigeri, Raffaella; Crescentini, Filippo; Pipitone, Nicolò; Salvarani, Carlo

    2016-01-01

    Abstract This study evaluated the frequency, timing, and characteristics of flares in a large cohort of Italian patients with biopsy-proven giant cell arteritis (GCA) and to identify factors at diagnosis able to predict the occurrence of flares. We evaluated 157 patients with biopsy-proven transmural GCA diagnosed and followed at the Rheumatology Unit of Reggio Emilia Hospital (Italy) for whom sufficient information was available from the time of diagnosis until at least 4 years of follow-up. Fifty-seven patients (36.5%) experienced ≥1 flares. Fifty-one (46.4%) of the 110 total flares (88 relapses and 22 recurrences) were experienced during the first 2 years after diagnosis. The majority of relapses occurred with doses of prednisone ≤ 10 mg/day (82.9%), whereas only 3.4% of relapses occurred for doses ≥ 25 mg/day. Polymyalgia rheumatica (46.5%) and cranial symptoms (41.9%) were the most frequent manifestations at the time of the first relapse. Cumulative prednisone dose during the first year and total cumulative prednisone dose were significantly higher in flaring patients compared with those without flares (7.8 ± 2.4 vs 6.7 ± 2.4 g, P = 0.02; 15.5 ± 8.9 vs 10.0 ± 9.2 g, P = 0.0001, respectively). The total duration of prednisone treatment was longer in flaring patients (58 ± 44 vs 30 ± 30 months, P = 0.0001). Patients with disease flares had at diagnosis more frequently systemic manifestations (P = 0.02) and fever ≥ 38°C (P = 0.02), significantly lower hemoglobin levels (P = 0.05), more frequent presence at temporal artery biopsy (TAB) specimens of giant cells (P = 0.04) and intraluminal acute thrombosis (P = 0.007), and more moderate/severe arterial inflammation (P = 0.009) compared with those without flares. In the multivariate model fever ≥ 38 °C (hazard ratio 2.14; 95% confidence interval, 1.06–4.32, P = 0.03) and the severity of inflammatory infiltrate

  1. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    International Nuclear Information System (INIS)

    Yu, Z.X.; Ma, Y.Z.; Zhao, Y.L.; Huang, J.B.; Wang, W.Z.; Moliere, M.; Liao, H.L.

    2017-01-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P_(_0_0_2_)_. It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  2. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.X., E-mail: zexin.yu@utbm.fr [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Ma, Y.Z., E-mail: yangzhou.ma@outlook.com [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Zhao, Y.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Huang, J.B.; Wang, W.Z. [Key Lab of Safety Science of Pressurized System, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Moliere, M.; Liao, H.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France)

    2017-08-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P{sub (002).} It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  3. ["Flare-up" during endodontic treatment--etiology and management].

    Science.gov (United States)

    Zuckerman, O; Metzger, Z; Sela, G; Lin, S

    2007-04-01

    "Flare-ups" during or following endodontic treatment are not uncommon. A "Flare-up" refers to post-operative pain and/or swelling resulting from bacterial, mechanical or chemical irritation. Prompt diagnosis and treatment are essential for reducing patients' pain and discomfort. Prevention of bacterial, chemical or mechanical invasion to the periapical tissues is the best approach. Other treatment modalities which reduce the probability of periradicular tissue irritation should also be adopted. Etiology, prevention, diagnosis and treatment options of "flare-up" cases are discussed as well as indications for analgesics, in accordance with the severity of the pain.

  4. Solar Flares and the High Energy Solar Spectroscopic Imager (HESSI)

    Science.gov (United States)

    Holman, Gordon D.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Solar flares are the biggest explosions in the solar system. They are important both for understanding explosive events in the Universe and for their impact on human technology and communications. The satellite-based HESSI is designed to study the explosive release of energy and the acceleration of electrons, protons, and other charged particles to high energies in solar flares. HESSI produces "color" movies of the Sun in high-energy X rays and gamma rays radiated by these energetic particles. HESSI's X-ray and gamma-ray images of flares are obtained using techniques similar to those used in radio interferometry. Ground-based radio observations of the Sun provide an important complement to the HESSI observations of solar flares. I will describe the HESSI Project and the high-energy aspects of solar flares, and how these relate to radio astronomy techniques and observations.

  5. Flare activity on UV Ceti: visible and IUE observations

    International Nuclear Information System (INIS)

    Phillips, K.J.H.; Bromage, G.E.; Dufton, P.L.; Keenan, F.P.; Kingston, A.E.

    1988-01-01

    Simultaneous far-ultraviolet (IUE) spectroscopy and optical photometry and spectrophotometry of a flare on UV Ceti are reported. The flare reached ΔU=2 mag but showed only modest enhancements in the IUE spectra. The optical spectrophotometry indicated broadened Balmer line profiles during the flare, with Hβ and Hγ clearly showing red wings (∼ 100 km s -1 ). The results are compared with other IUE and optical observations of UV Ceti, and their solar analogues. (author)

  6. ELECTRON ACCELERATION IN PULSAR-WIND TERMINATION SHOCKS: AN APPLICATION TO THE CRAB NEBULA GAMMA-RAY FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, John J.; Becker, Peter A.; Dermer, Charles D. [Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030-4444 (United States); Finke, Justin D., E-mail: jkroon@gmu.edu, E-mail: pbecker@gmu.edu, E-mail: charlesdermer@outlook.com, E-mail: justin.finke@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-12-20

    The γ -ray flares from the Crab Nebula observed by AGILE and Fermi -LAT reaching GeV energies and lasting several days challenge the standard models for particle acceleration in pulsar-wind nebulae because the radiating electrons have energies exceeding the classical radiation-reaction limit for synchrotron. Previous modeling has suggested that the synchrotron limit can be exceeded if the electrons experience electrostatic acceleration, but the resulting spectra do not agree very well with the data. As a result, there are still some important unanswered questions about the detailed particle acceleration and emission processes occurring during the flares. We revisit the problem using a new analytical approach based on an electron transport equation that includes terms describing electrostatic acceleration, stochastic wave-particle acceleration, shock acceleration, synchrotron losses, and particle escape. An exact solution is obtained for the electron distribution, which is used to compute the associated γ -ray synchrotron spectrum. We find that in our model the γ -ray flares are mainly powered by electrostatic acceleration, but the contributions from stochastic and shock acceleration play an important role in producing the observed spectral shapes. Our model can reproduce the spectra of all the Fermi -LAT and AGILE flares from the Crab Nebula, using magnetic field strengths in agreement with the multi-wavelength observational constraints. We also compute the spectrum and duration of the synchrotron afterglow created by the accelerated electrons, after they escape into the region on the downstream side of the pulsar-wind termination shock. The afterglow is expected to fade over a maximum period of about three weeks after the γ -ray flare.

  7. Validation of treatment escalation as a definition of atopic eczema flares.

    Directory of Open Access Journals (Sweden)

    Kim S Thomas

    Full Text Available Atopic eczema (AE is a chronic disease with flares and remissions. Long-term control of AE flares has been identified as a core outcome domain for AE trials. However, it is unclear how flares should be defined and measured.To validate two concepts of AE flares based on daily reports of topical medication use: (i escalation of treatment and (ii days of topical anti-inflammatory medication use (topical corticosteroids and/or calcineurin inhibitors.Data from two published AE studies (studies A (n=336 and B (n=60 were analysed separately. Validity and feasibility of flare definitions were assessed using daily global bother (scale 0 to 10 as the reference standard. Intra-class correlations were reported for continuous variables, and odds ratios and area under the receiver operator characteristic (ROC curve for binary outcome measures.Good agreement was found between both AE flare definitions and change in global bother: area under the ROC curve for treatment escalation of 0.70 and 0.73 in studies A and B respectively, and area under the ROC curve of 0.69 for topical anti-inflammatory medication use (Study A only. Significant positive relationships were found between validated severity scales (POEM, SASSAD, TIS and the duration of AE flares occurring in the previous week - POEM and SASSAD rose by half a point for each unit increase in number of days in flare. Smaller increases were observed on the TIS scale. Completeness of daily diaries was 95% for Study A and 60% for Study B over 16 weeks.Both definitions were good proxy indicators of AE flares. We found no evidence that 'escalation of treatment' was a better measure of AE flares than 'use of topical anti-inflammatory medications'. Capturing disease flares in AE trials through daily recording of medication use is feasible and appears to be a good indicator of long-term control.Current Controlled Trials ISRCTN71423189 (Study A.

  8. Photographic colorimetry of stellar flares in the Pleiades and Orion. II

    International Nuclear Information System (INIS)

    Mirzoian, L.V.; Chavushian, O.S.; Melikian, N.D.; Natsvlishvili, R.Sh.; Ambarian, V.V.; Brutian, G.A.

    1984-01-01

    Synchronous three-telescope UBV photographic colorimetry of Pleiades and Orion stellar flares obtained at Biurakan Astrophysical Observatory and Abastumani Astrophysical Observatory during 86 observing hours in 1980 and 1981 is presented. The data are compiled in tables and discussed in terms of color differences appearing at different stages of a flare. A total of 32 flares are observed (25 in the Pleiades and 7 in Orion), and four new flare stars are identified in each region. 12 references

  9. The potential near-source ozone impacts of upstream oil and gas industry emissions.

    Science.gov (United States)

    Olaguer, Eduardo P

    2012-08-01

    Increased drilling in urban areas overlying shale formations and its potential impact on human health through decreased air quality make it important to estimate the contribution of oil and gas activities to photochemical smog. Flares and compressor engines used in natural gas operations, for example, are large sources not only of NOx but also offormaldehyde, a hazardous air pollutant and powerful ozone precursor We used a neighborhood scale (200 m horizontal resolution) three-dimensional (3D) air dispersion model with an appropriate chemical mechanism to simulate ozone formation in the vicinity ofa hypothetical natural gas processing facility, based on accepted estimates of both regular and nonroutine emissions. The model predicts that, under average midday conditions in June, regular emissions mostly associated with compressor engines may increase ambient ozone in the Barnett Shale by more than 3 ppb beginning at about 2 km downwind of the facility, assuming there are no other major sources of ozone precursors. Flare volumes of 100,000 cubic meters per hour ofnatural gas over a period of 2 hr can also add over 3 ppb to peak 1-hr ozone somewhatfurther (>8 km) downwind, once dilution overcomes ozone titration and inhibition by large flare emissions of NOx. The additional peak ozone from the hypothetical flare can briefly exceed 10 ppb about 16 km downwind. The enhancements of ambient ozone predicted by the model are significant, given that ozone control strategy widths are of the order of a few parts per billion. Degrading the horizontal resolution of the model to 1 km spuriously enhances the simulated ozone increases by reducing the effectiveness of ozone inhibition and titration due to artificial plume dilution.

  10. Synchronous photoelectrical observations of flare stars in the visible and near infrared ranges

    International Nuclear Information System (INIS)

    Bruevich, V.V.; Kilyachkov, N.N.; Shevchenko, V.S.; Burnashov, V.I.; Grinin, V.P.; Koryshev, V.V.; Shakhovskaya, N.I.

    1980-01-01

    The results of synchronous photoelectrical observations of the AD Leo and EV Lac flare stars made in 1975 in the Crimea in B-filter and in the near infrared region (i-band, lambdasub(ef) approximately 0.85 μm) and the observations of the UV Cet and EV Lac stars made in 1976 in the Astronomical Institute Uzbek SSR in three passbands: U, isub(TiO)(lambdasub(ef)=0.71 μ) and isub(C)(lambdasub(ef)=0.80μm) are given. Practically all strong flares in the visible spectral range were followed by the IR-flares. In about 70% of the cases the predicted infrared negative preflares were observed. The amplitudes (in erg/s) of the negative flares are comparable with the amplitude of the optical flares. The analysis of the observed data shows that: a) the amplitudes and the energies of the positive IR flares are in average the larger the stronger is the optical flare; b) the amplitudes of the negative IR preflares are on the contrary the smaller the stronger is the optical flare; c) there are infrared flares the main energy out of which takes place in the infrared range of wavelengths; d) The U-i color shows a positive correlation with the amplitude of the flare in U: the stronger is the flare the bluer is its radiation

  11. Feasibility and Domain Validation of Rheumatoid Arthritis (RA) Flare Core Domain Set

    DEFF Research Database (Denmark)

    Bartlett, Susan J; Bykerk, Vivian P; Cooksey, Roxanne

    2015-01-01

    , and stiffness scores averaged ≥ 2 times higher (2 of 11 points) in flaring individuals. Correlations between flare domains and corresponding legacy instruments were obtained: r = 0.46 to 0.93. A combined definition (patient report of flare and 28-joint Disease Activity Score increase) was evaluated in 2 other...... provided input for stiffness, self-management, contextual factors, and measurement considerations. RESULTS: Flare data from 501 patients in an observational study indicated 39% were in flare, with mean (SD) severity of 6.0 (2.6) and 55% lasting > 14 days. Pain, physical function, fatigue, participation...

  12. Periodic Recurrence Patterns In X-Ray Solar Flare Appearances

    Science.gov (United States)

    Gyenge, N.; Erdélyi, R.

    2018-06-01

    The temporal recurrence of micro-flare events is studied for a time interval before and after of major solar flares. Our sample is based on the X-ray flare observations by the Geostationary Operational Environmental Satellite (GOES) and Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The analyzed data contain 1330/301 M-class and X-class GOES/RHESSI energetic solar flares and 4062/4119 GOES/RHESSI micro-flares covering the period elapse since 2002. The temporal analysis of recurrence, by Fast Fourier Transform, of the micro-flares, shows multiple significant periods. Based on the GOES and RHESSI data, the temporal analysis also demonstrates that multiple periods manifest simultaneously in both statistical samples without any significant shift over time. In the GOES sample, the detected significant periods are: 11.33, 5.61, 3.75, 2.80, and 2.24 minutes. The RHESSI data show similar significant periods at 8.54, 5.28, 3.66, 2.88, and 2.19 minutes. The periods are interpreted as signatures of standing oscillations, with the longest period (P 1) being the fundamental and others being higher harmonic modes. The period ratio of the fundamental and higher harmonics (P 1/P N ) is also analyzed. The standing modes may be signatures of global oscillations of the entire solar atmosphere encompassing magnetized plasma from the photosphere to the corona in active regions.

  13. Relation between gamma-ray emission, radio bursts, and proton fluxes from solar flares

    International Nuclear Information System (INIS)

    Fomichev, V.V.; Chertok, I.M.

    1985-01-01

    Data on solar gamma-ray flares, including 24 flares with gamma-ray lines, recorded up to June 1982, are analyzed. It is shown that from the point of view of radio emission the differences between flares with and without gamma-ray lines has a purely quantitative character: the former are accompanied by the most intense microwave bursts. Meter type II bursts are not a distinctive feature of flares with gamma-ray lines. Pulsed flares, regardless of the presence or absence of gamma-ray lines, are not accompanied by significant proton fluxes at the earth. On the whole, contrary to the popular opinion in the literature, flares with gamma-ray lines do not display a deficit of proton flux in interplanetary space in comparison with similar flares without gamma-ray lines. The results of quantitative diagnostics of proton flares based on radio bursts are not at variance with the presence of flares without detectable gamma-ray emission in lines but with a pronounced increase in the proton flux at the earth. 23 references

  14. Decision 99-13: Crestar Energy Inc. applications to construct and operate sour gas batteries and pipelines, Vulcan Field

    International Nuclear Information System (INIS)

    1999-06-01

    On 1 December 1998, the applicant applied pursuant to Part 4 of the Pipeline Act and Section 7.001 of the Oil and Gas Conservation Regulations for approval to construct and operate a sour gas pipeline and various surface facilities to tie in three wells. These are located at Legal Subdivision 12 of Section 36, Township 16, Range 24, West of the fourth Meridian (12-36 facility), Lsd 10-35-16-24 WM4 (10-35 facility), and Lsd 7-26-16-24 WM4 (7-26 facility), to an existing pipeline and proposed surface facility at Lsd 16-16-16-24 WM4. The 10-35, 7-26 and 16-16 facilities would each have a separator, a flare knockout drum, and a flare stack. The 12-36 facility would have two separators, one for each of the two producing zones at the 12-36 facility, a flare knockout drum, and flare stack. A compressor would be installed at the 16-16 facility. All fluids would be measured and re-injected into the pipeline for removal at the 16-16 facility. All proposed flare stacks would consists of a continuously burning sweet gas pilot and would be used for emergencies, routine well servicing, and pigging operations only. The pipeline would be designated as a Level 1 facility, and would transport up to 18 moles of hydrogen sulfide per kilomole of natural gas. Although the Board approved Application No. 1037084 after carefully considering the evidence, subject to meeting all the regulatory requirements and conditions set out in Attachment 1, it rejected Application No. 1033453

  15. Time-dependent solution for a one-dimensional piston problem in a non-ideal gas

    International Nuclear Information System (INIS)

    Purohit, S.C.

    1980-01-01

    In this article we study the effect of a non-ideal gas parameter on the piston (contact) surface when a strong shock moves into a non-uniform medium. The solution corresponding to the ideal gas can be obtained as a particular case of the analysis. (orig.)

  16. Detection of the Acceleration Site in a Solar Flare

    Science.gov (United States)

    Fleishman, Gregory D.; Kontar, E. P.; Nita, G. M.; Gary, D. E.

    2011-05-01

    We report the observation of an unusual cold, tenuous solar flare (ApJL, v. 731, p. L19, 2011), which reveals itself via numerous and prominent non-thermal manifestations, while lacking any noticeable thermal emission signature. RHESSI hard X-rays and 0.1-18 GHz radio data from OVSA and Phoenix-2 show copious electron acceleration (1035 electrons per second above 10 keV) typical for GOES M-class flares with electrons energies up to 100 keV, but GOES temperatures not exceeding 6.1 MK. The HXR footpoints and coronal radio sources belong, supposedly, to a single magnetic loop, which departs strongly from the corresponding potential loop (obtained from a photospheric extrapolation) in agreement with the apparent need of a non-potential magnetic field structure to produce a flare. The imaging, temporal, and spectral characteristics of the flare have led us to a firm conclusion that the bulk of the microwave continuum emission from this flare was produced directly in the acceleration region. We found that the electron acceleration efficiency is very high in the flare, so almost all available thermal electrons are eventually accelerated. However, given a relatively small flaring volume and rather low thermal density at the flaring loop, the total energy release turned out to be insufficient for a significant heating of the coronal plasma or for a prominent chromospheric response giving rise to chromospheric evaporation. Some sort of stochastic acceleration process is needed to account for an approximately energy-independent lifetime of about 3 s for the electrons in the acceleration region. This work was supported in part by NSF grants AGS-0961867, AST-0908344, and NASA grants NNX10AF27G and NNX11AB49G to New Jersey Institute of Technology. This work was supported by a UK STFC rolling grant, STFC/PPARC Advanced Fellowship, and the Leverhulme Trust, UK. Financial support by the European Commission through the SOLAIRE and HESPE Networks is gratefully acknowledged.

  17. Magnetogasdynamic spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes

    Science.gov (United States)

    Nath, G.; Vishwakarma, J. P.

    2016-11-01

    Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.

  18. Measurements and modeling of total solar irradiance in X-class solar flares

    International Nuclear Information System (INIS)

    Moore, Christopher Samuel; Chamberlin, Phillip Clyde; Hock, Rachel

    2014-01-01

    The Total Irradiance Monitor (TIM) from NASA's SOlar Radiation and Climate Experiment can detect changes in the total solar irradiance (TSI) to a precision of 2 ppm, allowing observations of variations due to the largest X-class solar flares for the first time. Presented here is a robust algorithm for determining the radiative output in the TIM TSI measurements, in both the impulsive and gradual phases, for the four solar flares presented in Woods et al., as well as an additional flare measured on 2006 December 6. The radiative outputs for both phases of these five flares are then compared to the vacuum ultraviolet (VUV) irradiance output from the Flare Irradiance Spectral Model (FISM) in order to derive an empirical relationship between the FISM VUV model and the TIM TSI data output to estimate the TSI radiative output for eight other X-class flares. This model provides the basis for the bolometric energy estimates for the solar flares analyzed in the Emslie et al. study.

  19. Performance of a micro-strip gas chamber in solution X-ray scattering

    CERN Document Server

    Toyokawa, H; Inoko, Y; Nagayoshi, T; Nishi, Y; Nishikawa, Y; Ochi, A; Suzuki, M; Tanimori, T

    2001-01-01

    The performance of a Micro-Strip Gas Chamber in solution X-ray scattering was studied at the RIKEN structural biology beamline I of the SPring-8 facility. The practical dynamic range was confirmed to be approx 1,000,000 : 1 by measuring S sup - sup 4 decay from a polystyrene latex solution. Steep troughs of scattering profile from an apoferritin solution were clearly obtained without smearing. An unfolding process of a pH jump of cytochrome c was measured. A time resolution of 500 mu s was achieved.

  20. Optical flare observed in the flaring gamma-ray blazar Ton 599

    Science.gov (United States)

    Pursimo, Tapio; Sagues, Ana; Telting, John; Ojha, Roopesh

    2017-11-01

    We report optical photometry of the flat spectrum radio quasar Ton 599, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#10931, ATel#10937).

  1. A ``perfect'' Late Phase Flare Loop: X-ray And Radio Studies

    Science.gov (United States)

    Bain, Hazel; Fletcher, L.

    2009-05-01

    We present observations of a GOES X3.1 class flare which occurred on the 24th August 2002. The event was observed by a number of instruments including RHESSI, TRACE and NoRH. This flare is particularly interesting due to its position and orientation on the west limb of the Sun. The flare appears to be perpendicular to the line of sight making it possible to ascertain the geometrical parameters of the post flare arcade loops. We investigate the decay phase of the flare by comparing X-ray and radio observations of the post flare arcade loops with models of soft x-ray and thermal gyrosynchrotron emission to characterise the electron distribution present within the loop. HMB gratefully acknowledges the support of an SPD and STFC studentship. LF gratefully acknowledges the support of an STFC Rolling Grant, and financial support by the European Commission through the SOLAIRE Network (MTRN-CT_2006-035484)

  2. Reconnection in Solar Flares: Outstanding Questions Hiroaki Isobe ...

    Indian Academy of Sciences (India)

    Although the idea of magnetic reconnection for explaining the energy release in solar flares had been proposed many decades ago (Parker 1957; Sweet. 1958) it was after Yohkoh (Ogawara et al. 1991) observations that the reality of mag- netic reconnection occurring during solar flares was established. Examples of evi-.

  3. Thermal x-rays and deuterium production in stellar flares

    International Nuclear Information System (INIS)

    Colgate, S.A.

    1977-01-01

    The x-ray spectrum of flares is shown to be necessarily thermal up to greater than or equal to 200 keV because the self magnetic field of any electron stream required for a thick or thin target source is inconsistently large. The resulting flare model can then be related to stellar luminosity, convection and magnetic fields to result in a maximum possible γ-burst (Mullan, 1976) and continuous x-ray flux. One of the most striking isotopic anomalies observed is the extreme enrichment of Helium (3) in some solar flares and the mysterious depletion of deuterium. It is discussed how deuterium may be produced and emitted in the largest flares associated with γ-bursts but in amounts insufficient to support the tentative conclusion of Colemen and Worden

  4. Thermodynamics of supra-arcade downflows in solar flares

    Science.gov (United States)

    Chen, Xin; Liu, Rui; Deng, Na; Wang, Haimin

    2017-10-01

    Context. Supra-arcade downflows (SADs) have been frequently observed during the gradual phase of solar flares near the limb. In coronal emission lines sensitive to flaring plasmas, they appear as tadpole-like dark voids against the diffuse fan-shaped "haze" above, flowing toward the well-defined flare arcade. Aims: We aim to investigate the evolution of SADs' thermal properties, and to shed light on the formation mechanism and physical processes of SADs. Methods: We carefully studied several selected SADs from two flare events and calculated their differential emission measures (DEMs) as well as DEM-weighted temperatures using data obtained by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamic Observatory. Results: Our analysis shows that SADs are associated with a substantial decrease in DEM above 4 MK, which is 1-3 orders of magnitude smaller than the surrounding haze as well as the region before or after the passage of SADs, but comparable to the quiet corona. There is no evidence for the presence of the SAD-associated hot plasma (>20 MK) in the AIA data, and this decrease in DEM does not cause any significant change in the DEM distribution as well as the DEM-weighted temperature, which supports this idea that SADs are density depletion. This depression in DEM rapidly recovers in the wake of the SADs studied, generally within a few minutes, suggesting that they are discrete features. In addition, we found that SADs in one event are spatio-temporally associated with the successive formation of post-flare loops along the flare arcade. Movies associated to Figs. A.1 and A.2 are available at http://www.aanda.org

  5. Latitudinal distribution of soft X-ray flares and dispairty in butterfly diagram

    Science.gov (United States)

    Pandey, K. K.; Yellaiah, G.; Hiremath, K. M.

    2015-04-01

    We present statistical analysis of about 63000 soft X-ray flare (class≥C) observed by geostationary operational environmental satellite (GOES) during the period 1976-2008. Class wise occurrence of soft X-ray (SXR) flare is in declining trend since cycle 21. The distribution pattern of cycle 21 shows the transit of hemispheric dominance of flare activity from northern to southern hemisphere and remains there during cycle 22 and 23. During the three cycles, 0-100, 21-300 latitude belts in southern hemisphere (SH) and 31-400 latitude belt in northern hemisphere (NH) are mightier. The 11-200 latitude belt of both hemisphere is mightiest. Correlation coefficient between consecutive latitude appears to be increasing from equator to poleward in northern hemisphere whereas pole to equatorward in southern hemisphere. Slope of the regression line fitted with asymmetry time series of daily flare counts is negative in all three cycles for different classes of flares. The yearly asymmetry curve fitted by a sinusoidal function varies from 5.6 to 11 years period and depends upon the intensity of flare. Variation, of curve fitted with wings of butterfly diagram, from first to second order polynomial suggests that latitudinal migration of flare activity varies from cycle to cycle, northern to southern hemisphere. The variation in slope of the butterfly wing of different flare class indicates the non uniform migration of flare activity.

  6. Recurrent flares in active region NOAA 11283

    Science.gov (United States)

    Romano, P.; Zuccarello, F.; Guglielmino, S. L.; Berrilli, F.; Bruno, R.; Carbone, V.; Consolini, G.; de Lauretis, M.; Del Moro, D.; Elmhamdi, A.; Ermolli, I.; Fineschi, S.; Francia, P.; Kordi, A. S.; Landi Degl'Innocenti, E.; Laurenza, M.; Lepreti, F.; Marcucci, M. F.; Pallocchia, G.; Pietropaolo, E.; Romoli, M.; Vecchio, A.; Vellante, M.; Villante, U.

    2015-10-01

    Context. Flares and coronal mass ejections (CMEs) are solar phenomena that are not yet fully understood. Several investigations have been performed to single out their related physical parameters that can be used as indices of the magnetic complexity leading to their occurrence. Aims: In order to shed light on the occurrence of recurrent flares and subsequent associated CMEs, we studied the active region NOAA 11283 where recurrent M and X GOES-class flares and CMEs occurred. Methods: We use vector magnetograms taken by HMI/SDO to calculate the horizontal velocity fields of the photospheric magnetic structures, the shear and the dip angles of the magnetic field, the magnetic helicity flux distribution, and the Poynting fluxes across the photosphere due to the emergence and the shearing of the magnetic field. Results: Although we do not observe consistent emerging magnetic flux through the photosphere during the observation time interval, we detected a monotonic increase of the magnetic helicity accumulated in the corona. We found that both the shear and the dip angles have high values along the main polarity inversion line (PIL) before and after all the events. We also note that before the main flare of X2.1 GOES class, the shearing motions seem to inject a more significant energy than the energy injected by the emergence of the magnetic field. Conclusions: We conclude that the very long duration (about 4 days) of the horizontal displacement of the main photospheric magnetic structures along the PIL has a primary role in the energy release during the recurrent flares. This peculiar horizontal velocity field also contributes to the monotonic injection of magnetic helicity into the corona. This process, coupled with the high shear and dip angles along the main PIL, appears to be responsible for the consecutive events of loss of equilibrium leading to the recurrent flares and CMEs. A movie associated to Fig. 4 is available in electronic form at http://www.aanda.org

  7. Amino acid salt solutions as solvents in CO2 capture from flue gas

    DEFF Research Database (Denmark)

    Lerche, Benedicte Mai; Thomsen, Kaj; Stenby, Erling Halfdan

    New solvents based on the salts of amino acids have emerged as an alternative to the alkanolamine solutions, for the chemical absorption of CO2 from flue gas. But only few studies on amino acids as CO2 capturing agents have been performed so far. One of the interesting features of amino acid salt...... solutions is their ability to form solid precipitates upon the absorption of CO2. The occurrence of crystallization offers the possibility of increasing the CO2 loading capacity of the solvent. However, precipitation can also have negative effect on the CO2 capture process. The chemical nature of the solid...... of glycine, taurine, and lysine, while in the case of proline, and glutamic acid, the precipitate was found to be bicarbonate. These results give an important contribution to further understanding the potential of amino acid salt solutions in CO2 capture from flue gas....

  8. “Orphan” γ-Ray Flares and Stationary Sheaths of Blazar Jets

    Science.gov (United States)

    MacDonald, Nicholas R.; Jorstad, Svetlana G.; Marscher, Alan P.

    2017-11-01

    Blazars exhibit flares across the entire electromagnetic spectrum. Many γ-ray flares are highly correlated with flares detected at longer wavelengths; however, a small subset appears to occur in isolation, with little or no correlated variability at longer wavelengths. These “orphan” γ-ray flares challenge current models of blazar variability, most of which are unable to reproduce this type of behavior. MacDonald et al. have developed the Ring of Fire model to explain the origin of orphan γ-ray flares from within blazar jets. In this model, electrons contained within a blob of plasma moving relativistically along the spine of the jet inverse-Compton scatter synchrotron photons emanating off of a ring of shocked sheath plasma that enshrouds the jet spine. As the blob propagates through the ring, the scattering of the ring photons by the blob electrons creates an orphan γ-ray flare. This model was successfully applied to modeling a prominent orphan γ-ray flare observed in the blazar PKS 1510-089. To further support the plausibility of this model, MacDonald et al. presented a stacked radio map of PKS 1510-089 containing the polarimetric signature of a sheath of plasma surrounding the spine of the jet. In this paper, we extend our modeling and stacking techniques to a larger sample of blazars: 3C 273, 4C 71.01, 3C 279, 1055+018, CTA 102, and 3C 345, the majority of which have exhibited orphan γ-ray flares. We find that the model can successfully reproduce these flares, while our stacked maps reveal the existence of jet sheaths within these blazars.

  9. The Solar Flare: A Strongly Turbulent Particle Accelerator

    Science.gov (United States)

    Vlahos, L.; Krucker, S.; Cargill, P.

    The topics of explosive magnetic energy release on a large scale (a solar flare) and particle acceleration during such an event are rarely discussed together in the same article. Many discussions of magnetohydrodynamic (MHD) mod- eling of solar flares and/or CMEs have appeared (see [143] and references therein) and usually address large-scale destabilization of the coronal mag- netic field. Particle acceleration in solar flares has also been discussed exten- sively [74, 164, 116, 166, 87, 168, 95, 122, 35] with the main emphasis being on the actual mechanisms for acceleration (e.g., shocks, turbulence, DC electric fields) rather than the global magnetic context in which the acceleration takes place.

  10. Impulsiveness and energetics in solar flares with and without type II radio bursts - A comparison of hard X-ray characteristics for over 2500 solar flares

    Science.gov (United States)

    Pearson, Douglas H.; Nelson, Robert; Kojoian, Gabriel; Seal, James

    1989-01-01

    The hard X-ray characteristics of more than 2500 solar flares are used to study the relative size, impulsiveness, and energetics of flares with and without type II radio bursts. A quantitative definition of the hard X-ray impulsiveness is introduced, which may be applied to a large number of events unambiguously. It is found that the flares with type II bursts are generally not significantly larger, more impulsive, or more energetic than those without type II bursts. Also, no evidence is found to suggest a simple classification of the flares as either 'impulsive' or 'gradual'. Because type II bursts are present even in small flares with relatively unimpulsive energy releases, it is concluded that changes in the ambient conditions of the solar atmosphere causing an unusually low Alfven speed may be important in the generation of the shock wave that produces type II radio bursts.

  11. Flaring red dwarf stars: news from Crimea

    International Nuclear Information System (INIS)

    Gershberg, Roald E

    1998-01-01

    Important phenomena are briefly described which have recently been discovered in the Crimean studies of flaring red dwarf stars believed to be the most common type of variable stars in the Galaxy. These phenomena include (i) long-lived radiation from a blueshifted component in the ionized-helium λ 4686 A emission line in the active state of one such star, (ii) a long-lived absorption component in the stellar flare light curves with a lifetime exceeding that of the conventional flare emission, and (iii) solarcycle-like activity periodicity of the star EV Lac, whose mass is only 0.3 solar masses. In theoretical terms, a red dwarf star spot model is constructed which, in contrast to the commonly accepted model, agrees well with the solar spot picture. (physics of our days)

  12. Flaring red dwarf stars: news from Crimea

    Energy Technology Data Exchange (ETDEWEB)

    Gershberg, Roald E [Crimean Astrophysical Observatory, Nauchnyi, Crimea (Ukraine)

    1998-08-31

    Important phenomena are briefly described which have recently been discovered in the Crimean studies of flaring red dwarf stars believed to be the most common type of variable stars in the Galaxy. These phenomena include (i) long-lived radiation from a blueshifted component in the ionized-helium {lambda} 4686 A emission line in the active state of one such star, (ii) a long-lived absorption component in the stellar flare light curves with a lifetime exceeding that of the conventional flare emission, and (iii) solarcycle-like activity periodicity of the star EV Lac, whose mass is only 0.3 solar masses. In theoretical terms, a red dwarf star spot model is constructed which, in contrast to the commonly accepted model, agrees well with the solar spot picture. (physics of our days)

  13. Slipping magnetic reconnection during an X-class solar flare observed by SDO/AIA

    Energy Technology Data Exchange (ETDEWEB)

    Dudík, J.; Del Zanna, G.; Mason, H. E. [DAMTP, CMS, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Janvier, M. [Department of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); Aulanier, G.; Schmieder, B. [LESIA, Observatoire de Paris, UMR 8109 (CNRS), F-92195 Meudon Principal Cedex (France); Karlický, M., E-mail: J.Dudik@damtp.cam.ac.uk, E-mail: mjanvier@maths.dundee.ac.uk [Astronomical Institute of the Academy of Sciences of the Czech Republic, Fričova 298, 251 65 Ondřejov (Czech Republic)

    2014-04-01

    We present SDO/AIA observations of an eruptive X-class flare of 2012 July 12, and compare its evolution with the predictions of a three-dimensional (3D) numerical simulation. We focus on the dynamics of flare loops that are seen to undergo slipping reconnection during the flare. In the Atmospheric Imaging Assembly (AIA) 131 Å observations, lower parts of 10 MK flare loops exhibit an apparent motion with velocities of several tens of km s{sup –1} along the developing flare ribbons. In the early stages of the flare, flare ribbons consist of compact, localized bright transition-region emission from the footpoints of the flare loops. A differential emission measure analysis shows that the flare loops have temperatures up to the formation of Fe XXIV. A series of very long, S-shaped loops erupt, leading to a coronal mass ejection observed by STEREO. The observed dynamics are compared with the evolution of magnetic structures in the 'standard solar flare model in 3D.' This model matches the observations well, reproducing the apparently slipping flare loops, S-shaped erupting loops, and the evolution of flare ribbons. All of these processes are explained via 3D reconnection mechanisms resulting from the expansion of a torus-unstable flux rope. The AIA observations and the numerical model are complemented by radio observations showing a noise storm in the metric range. Dm-drifting pulsation structures occurring during the eruption indicate plasmoid ejection and enhancement of the reconnection rate. The bursty nature of radio emission shows that the slipping reconnection is still intermittent, although it is observed to persist for more than an hour.

  14. On the Importance of the Flare's Late Phase for the Solar Extreme Ultraviolet Irradiance

    Science.gov (United States)

    Woods, Thomas N.; Eparvier, Frank; Jones, Andrew R.; Hock, Rachel; Chamberlin, Phillip C.; Klimchuk, James A.; Didkovsky, Leonid; Judge, Darrell; Mariska, John; Bailey, Scott; hide

    2011-01-01

    The new solar extreme ultraviolet (EUV) irradiance observations from NASA Solar Dynamics Observatory (SDO) have revealed a new class of solar flares that are referred to as late phase flares. These flares are characterized by the hot 2-5 MK coronal emissions (e.g., Fe XVI 33.5 nm) showing large secondary peaks that appear many minutes to hours after an eruptive flare event. In contrast, the cool 0.7-1.5 MK coronal emissions (e.g., Fe IX 17.1 nm) usually dim immediately after the flare onset and do not recover until after the delayed second peak of the hot coronal emissions. We refer to this period of 1-5 hours after the fl amrea sin phase as the late phase, and this late phase is uniquely different than long duration flares associated with 2-ribbon flares or large filament eruptions. Our analysis of the late phase flare events indicates that the late phase involves hot coronal loops near the flaring region, not directly related to the original flaring loop system but rather with the higher post-eruption fields. Another finding is that space weather applications concerning Earth s ionosphere and thermosphere need to consider these late phase flares because they can enhance the total EUV irradiance flare variation by a factor of 2 when the late phase contribution is included.

  15. Having the last gas

    Energy Technology Data Exchange (ETDEWEB)

    Freestone, N P; Phillips, P S; Hall, R [Nene College of Higher Education, Northampton (United Kingdom)

    1994-01-01

    Millions of visitors to the 1985 International Garden Festival in Liverpool were probably unaware that the landscape gardens they had come to enjoy were on top of approximately 10m t of domestic rubbish. Nor were they aware that this rubbish was generating a methane-rich gas that had necessitated installing a special extraction system to remove it from the site. At first this gas - landfill gas - was simply flared (burnt), but once it was realised that extraction would be need for at least 15 years it was decided to use the gas to generate electricity. This development is a good example of the potential, especially in the developed world, for using landfill gas produced in refuse tips as an additional and versatile energy source. This potential is analysed and the problems of exploitation examined. (2 figures). (author)

  16. Common SphinX and RHESSI observations of solar flares

    Science.gov (United States)

    Mrozek, T.; Gburek, S.; Siarkowski, M.; Sylwester, B.; Sylwester, J.; Gryciuk, M.

    The Polish X-ray spectrofotometer SphinX has observed a great number of solar flares in the year 2009 - during the most quiet solar minimum almost over the last 100 years. Hundreds of flares have been recorded due to excellent sensitivity of SphinX's detectors. The Si-PIN diodes are about 100 times more sensitive to X-rays than GOES X-ray Monitors. SphinX detectors were absolutely calibrated on Earth with a use of the BESSY synchrotron. In space observations were made in the range 1.2-15~keV with 480~eV energy resolution. SphinX data overlap with the low-energy end of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data. RHESSI detectors are quite old (7 years in 2009), but still sensitive enough to provide us with observations of extremely weak solar flares such as those which occurred in 2009. We have selected a group of flares simultaneously observed by RHESSI and SphinX and performed a spectroscopic analysis of the data. Moreover, we compared the physical parameters of these flares plasma. Preliminary results of the comparison show very good agreement between both instruments.

  17. A search for X-rays from UV Ceti flare stars

    International Nuclear Information System (INIS)

    Crannell, C.J.; Spangler, S.R.

    1975-01-01

    A search of the MIT/OSO-7 data has been made for evidence of X-ray emission from flares of UV Ceti flare stars. Observations from McDonald Observatory have been used to identify the times of optical flares. The only instance of coincident coverage occurred on 1974 January 21 UT at 03:43:26 GMT for a Δm = 0.86 flare of YZ CMi. No radio coverage of this particular event was obtained. Upper limits of 0.8, 1.0, and 0.7 photons/cm 2 s on the observed X-ray flux have been set for the energy ranges >= 15, >= 3, and 1-10 keV, respectively. (orig.) [de

  18. Incidence and factors related to flare-ups in a graduate endodontic programme.

    Science.gov (United States)

    Iqbal, M; Kurtz, E; Kohli, M

    2009-02-01

    To investigate the incidence and factors related to endodontic flare-ups in nonsurgical root canal treatment (NSRCT) cases completed by graduate endodontic residents at University of Pennsylvania, USA. Residents at University of Pennsylvania enter all clinical patient records into an electronic database called PennEndo database. Analysis of records of 6580 patients treated from September 2000 to July 2005 revealed a total of 26 patients with flare-ups (0.39%). Patients were categorized to have undergone flare-up when they attended for an unscheduled visit and active treatment, and when they suffered from severe pain and or swelling after initiation or continuation of NSRCT. SAS software was used to develop a logistic regression model with flare-up as a dependent variable. Independent variables included in the model were: history of previous pain, one vs. two visit NSRCT, periapical diagnosis, tooth type, rotary versus hand instrumentation, and lateral versus vertical compaction of gutta-percha. The odds for developing a flare-up in teeth with a periapical radiolucency were 9.64 times greater than teeth without a periapical radiolucency (P = 0.0090). There was no statistically significant difference in flare-ups between one and two visits NSRCT. The odds of developing a flare-up increased 40 fold when NSRCT was completed in three or more visits. However, this result may have been confounded by addition of an unscheduled visit in patients suffering from flare-ups. Other independent variables did not have any statistically significant correlations. A low percentage of patients experienced flare-ups during NSRCT procedures. The presence of a periapical lesion was the single most important predictor of flare-ups during NSRCT.

  19. Direct numerical simulation of hypersonic boundary-layer flow on a flared cone

    Energy Technology Data Exchange (ETDEWEB)

    Pruett, C.D. [James Madison Univ., Harrisonburg, VA (United States). Dept. of Math. and Comput. Sci.; Chang Chau-Lyan [High Technology Corporation, Hampton, VA 23666 (United States)

    1998-03-01

    The forced transition of the boundary layer on an axisymmetric flared cone in Mach 6 flow is simulated by the method of spatial direct numerical simulation (DNS). The full effects of the flared afterbody are incorporated into the governing equations and boundary conditions; these effects include nonzero streamwise surface curvature, adverse streamwise pressure gradient, and decreasing boundary-layer edge Mach number. Transition is precipitated by periodic forcing at the computational inflow boundary with perturbations derived from parabolized stability equation (PSE) methodology and based, in part, on frequency spectra available from physical experiments. Significant qualitative differences are shown to exist between the present results and those obtained previously for a cone without afterbody flare. In both cases, the primary instability is of second-mode type; however, frequencies are much higher for the flared cone because of the decrease in boundary-layer thickness in the flared region. Moreover, Goertler modes, which are linearly stable for the straight cone, are unstable in regions of concave body flare. Reynolds stresses, which peak near the critical layer for the straight cone, exhibit peaks close to the wall for the flared cone. The cumulative effect appears to be that transition onset is shifted upstream for the flared cone. However, the length of the transition zone may possibly be greater because of the seemingly more gradual nature of the transition process on the flared cone. (orig.) With 20 figs., 28 refs.

  20. Very low luminosity stars with very large amplitude flares

    International Nuclear Information System (INIS)

    Schaefer, B.E.

    1990-01-01

    CCD frames of CZ Cnc, KY Cep, the gamma-ray burster optical transient, and NSV 12006 are analyzed. Also studied are 549 archival photographic plates of the CZ Cnc field. These observations are compared with the data of Lovas (1976). Flare events on CZ Cnc are examined. Based on the data it is noted that CZ Cnc is a main-sequence star, has a magnitude of 16.1, a distance of 100 pc, occasional large-amplitude flares, and frequent flares with amplitudes greater than 4 mag. 36 refs

  1. Wavelength Dependence of Solar Flare Irradiation and its Influence on the Thermosphere

    Science.gov (United States)

    Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Qian, L.; Solomon, S.; Chamberlin, P.

    2012-01-01

    The wavelength dependence of solar flare enhancement is one of the important factors determining how the Thermosphere-Ionosphere (T-I) system response to flares. To investigate the wavelength dependence of solar flare, the Flare Irradiance Spectral Model (FISM) has been run for 34 X-class flares. The results show that the percentage increases of solar irradiance at flare peak comparing to pre-flare condition have a clear wavelength dependence. In the wavelength range between 0 - 195 nm, it can vary from 1% to 10000%. The solar irradiance enhancement is largest ( 1000%) in the XUV range (0 - 25 nm), and is about 100% in EUV range (25 - 120 nm). The influence of different wavebands on the T-I system during the October 28th, 2003 flare (X17.2-class) has also been examined using the latest version of National Center for Atmospheric Research (NCAR) Thermosphere- Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). While the globally integrated solar energy deposition is largest in the 0 - 14 nm waveband, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for 25 - 105 nm waveband. The effect of 122 - 195 nm is small in magnitude, but it decays slowly.

  2. THE CONFINED X-CLASS FLARES OF SOLAR ACTIVE REGION 2192

    Energy Technology Data Exchange (ETDEWEB)

    Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M., E-mail: julia.thalmann@uni-graz.at [Institute of Physics/IGAM, University of Graz, Universitätsplatz 5/II, 8010 Graz (Austria)

    2015-03-10

    The unusually large active region (AR) NOAA 2192, observed in 2014 October, was outstanding in its productivity of major two-ribbon flares without coronal mass ejections. On a large scale, a predominantly north–south oriented magnetic system of arcade fields served as a strong top and lateral confinement for a series of large two-ribbon flares originating from the core of the AR. The large initial separation of the flare ribbons, together with an almost absent growth in ribbon separation, suggests a confined reconnection site high up in the corona. Based on a detailed analysis of the confined X1.6 flare on October 22, we show how exceptional the flaring of this AR was. We provide evidence for repeated energy release, indicating that the same magnetic field structures were repeatedly involved in magnetic reconnection. We find that a large number of electrons was accelerated to non-thermal energies, revealing a steep power-law spectrum, but that only a small fraction was accelerated to high energies. The total non-thermal energy in electrons derived (on the order of 10{sup 25} J) is considerably higher than that in eruptive flares of class X1, and corresponds to about 10% of the excess magnetic energy present in the active-region corona.

  3. Impulsive phase of solar flares: theory

    International Nuclear Information System (INIS)

    Mackinnon, A.L.

    1986-01-01

    The paper reviews the theoretical interpretation of impulsive phase phenomena in solar flares. The impulsive phase is defined to be that period of approx. 10 - 100s duration, during which the flare radiative output undergoes its most rapid, dramatic increase and decrease. The interpretation of the various impulsive phase radiation signatures are examined, including the i) hard x-ray emission, ii) radio emission, iii) UV, Hα and white light emissions and iv) gamma-ray emission. The acceleration mechanisms are discussed with respect to candidate acceleration mechanisms, and the synthesis of the theory and observations. (UK)

  4. Current Fragmentation and Particle Acceleration in Solar Flares

    Science.gov (United States)

    Cargill, P. J.; Vlahos, L.; Baumann, G.; Drake, J. F.; Nordlund, Å.

    2012-11-01

    Particle acceleration in solar flares remains an outstanding problem in plasma physics and space science. While the observed particle energies and timescales can perhaps be understood in terms of acceleration at a simple current sheet or turbulence site, the vast number of accelerated particles, and the fraction of flare energy in them, defies any simple explanation. The nature of energy storage and dissipation in the global coronal magnetic field is essential for understanding flare acceleration. Scenarios where the coronal field is stressed by complex photospheric motions lead to the formation of multiple current sheets, rather than the single monolithic current sheet proposed by some. The currents sheets in turn can fragment into multiple, smaller dissipation sites. MHD, kinetic and cellular automata models are used to demonstrate this feature. Particle acceleration in this environment thus involves interaction with many distributed accelerators. A series of examples demonstrate how acceleration works in such an environment. As required, acceleration is fast, and relativistic energies are readily attained. It is also shown that accelerated particles do indeed interact with multiple acceleration sites. Test particle models also demonstrate that a large number of particles can be accelerated, with a significant fraction of the flare energy associated with them. However, in the absence of feedback, and with limited numerical resolution, these results need to be viewed with caution. Particle in cell models can incorporate feedback and in one scenario suggest that acceleration can be limited by the energetic particles reaching the condition for firehose marginal stability. Contemporary issues such as footpoint particle acceleration are also discussed. It is also noted that the idea of a "standard flare model" is ill-conceived when the entire distribution of flare energies is considered.

  5. Solar Features - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the...

  6. High-energy particles associated with solar flares

    International Nuclear Information System (INIS)

    Sakurai, K.; Klimas, A.J.

    1974-05-01

    High energy particles, the so-called solar cosmic rays, are often generated in association with solar flares, and then emitted into interplanetary space. These particles, consisting of electrons, protons, and other heavier nuclei, including the iron-group, are accelerated in the vicinity of the flare. By studying the temporal and spatial variation of these particles near the earth's orbit, their storage and release mechanisms in the solar corona and their propagation mechanism can be understood. The details of the nuclear composition and the rigidity spectrum for each nuclear component of the solar cosmic rays are important for investigating the acceleration mechanism in solar flares. The timing and efficiency of the acceleration process can also be investigated by using this information. These problems are described in some detail by using observational results on solar cosmic rays and associated phenomena. (U.S.)

  7. Giant Radio Flare of Cygnus X-3 in September 2016

    Science.gov (United States)

    Trushkin, S. A.; Nizhelskij, N. A.; Tsybulev, P. G.; Zhekanis, G. V.

    2017-06-01

    In the long-term multi-frequency monitoring program of the microquasars with RATAN-600 we discovered the giant flare from X-ray binary Cyg X-3 on 13 September 2016. It happened after 2000 days of the 'quiescent state' of the source passed after the former giant flare (˜18 Jy) in March 2011. We have found that during this quiet period the hard X-ray flux (Swift/BAT, 15-50 keV) and radio flux (RATAN-600, 11 GHz) have been strongly anti-correlated. Both radio flares occurred after transitions of the microquasar to a 'hypersoft' X-ray state that occurred in February 2011 and in the end of August 2016. The giant flare was predicted by us in the first ATel (Trushkin et al. (2016)). Indeed after dramatic decrease of the hard X-ray Swift 15-50 keV flux and RATAN 4- 11 GHz fluxes (a 'quenched state') a small flare (0.7 Jy at 4-11 GHz) developed on MJD 57632 and then on MJD 57644.5 almost simultaneously with X-rays radio flux rose from 0.01 to 15 Jy at 4.6 GHz during few days. The rise of the flaring flux is well fitted by a exponential law that could be a initial phase of the relativistic electrons generation by internal shock waves in the jets. Initially spectra were optically thick at frequencies lower 2 GHz and optically thin at frequencies higher 8 GHz with typical spectral index about -0.5. After maximum of the flare radio fluxes at all frequencies faded out with exponential law.

  8. Fermi -LAT Observations of High-energy Behind-the-limb Solar Flares

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Allafort, A.; Bottacini, E.; Cameron, R. A.; Charles, E. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bissaldi, E.; Caragiulo, M.; Costanza, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); Bonino, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino (Italy); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier (France); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Caraveo, P. A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, I-20133 Milano (Italy); Cavazzuti, E.; Ciprini, S. [Agenzia Spaziale Italiana (ASI) Science Data Center, I-00133 Roma (Italy); Cecchi, C., E-mail: nicola.omodei@stanford.edu, E-mail: vahep@stanford.edu, E-mail: melissa.pesce.rollins@pi.infn.it [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); and others

    2017-02-01

    We report on the Fermi -LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi -LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO . All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi -LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission.

  9. Far-ultraviolet and visible observations of flares on dMe stars

    International Nuclear Information System (INIS)

    Bromage, G.E.; Patchett, B.E.; Phillips, K.J.H.

    1983-01-01

    Four large flare events - one on each of the dMe stars UV Cet, AT Mic, EV Lac and EQ Peg - have been witnessed during a total of 17 1/2 hours of far-UV (lambdalambda1150-1950) IUE exposures. Some observational characteristics of these four events are compared. Two showed strong enhancements of chromospheric and transition-region line strengths. The other two did not, even though their visible flares were intense (ΔU approx. 2 mag.). The brightest UV flare spectrum (EQ Peg) is contrasted with that of the largest solar flare seen from 'Skylab'. (Auth.)

  10. MAGNETIC PROPERTIES OF SOLAR ACTIVE REGIONS THAT GOVERN LARGE SOLAR FLARES AND ERUPTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Toriumi, Shin [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Schrijver, Carolus J. [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Harra, Louise K. [UCL-Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Hudson, Hugh [SUPA School of Physics and Astronomy, University of Glasgow (United Kingdom); Nagashima, Kaori, E-mail: shin.toriumi@nao.ac.jp [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2017-01-01

    Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim of understanding the magnetic properties that govern such flares and eruptions, we systematically survey all flare events with Geostationary Orbiting Environmental Satellite levels of ≥M5.0 within 45° from disk center between 2010 May and 2016 April. These criteria lead to a total of 51 flares from 29 ARs, for which we analyze the observational data obtained by the Solar Dynamics Observatory . More than 80% of the 29 ARs are found to exhibit δ -sunspots, and at least three ARs violate Hale’s polarity rule. The flare durations are approximately proportional to the distance between the two flare ribbons, to the total magnetic flux inside the ribbons, and to the ribbon area. From our study, one of the parameters that clearly determine whether a given flare event is CME-eruptive or not is the ribbon area normalized by the sunspot area, which may indicate that the structural relationship between the flaring region and the entire AR controls CME productivity. AR characterization shows that even X-class events do not require δ -sunspots or strong-field, high-gradient polarity inversion lines. An investigation of historical observational data suggests the possibility that the largest solar ARs, with magnetic flux of 2 × 10{sup 23} Mx, might be able to produce “superflares” with energies of the order of 10{sup 34} erg. The proportionality between the flare durations and magnetic energies is consistent with stellar flare observations, suggesting a common physical background for solar and stellar flares.

  11. Heat Recovery From Tail Gas Incineration To Generate Power

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, Tarek

    2010-09-15

    Many industrial processes result in tail gas wastes that must be flared or incinerated to abide with environmental guidelines. Tail gas incineration occurs in several chemical processes resulting in high-temperature exhaust gas that simply go to the stack, thus wasting all that valuable heat! This paper discusses useful heat recovery and electric power generation utilizing available heat in exhaust gas from tail gas incinerators. This heat will be recovered in a waste-heat recovery boiler that will produce superheated steam to expand in a steam turbine to generate power. A detailed cost estimate is presented.

  12. Radiative hazard of solar flares in the nearterrestrial cosmic space

    International Nuclear Information System (INIS)

    Kolomenskij, A.V.; Petrov, V.M.; Zil', M.V.; Eremkina, T.M.

    1978-01-01

    Simulation of radiation enviroment due to solar cosmic rays was carried out in the near-terrestrial space. Systematized are the data on cosmic ray flux and spectra detected during 19-th and 20-th cycles of solar activity. 127 flares are considered with proton fluxes of more than 10 proton/cm 2 at energies higher than 30 MeV. Obtained are distribution functions of intervals between flares, flux distribution of flares and characteristic rigidity, and also distribution of magnetic disturbances over Dsub(st)-variation amplitude. The totality of these distributions presents the statistic model of radiation enviroment caused by solar flare protons for the period of maximum solar .activity. This model is intended for estimation of radiation hazard at manned cosmic flights

  13. HOOKED FLARE RIBBONS AND FLUX-ROPE-RELATED QSL FOOTPRINTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jie; Li, Hui [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Gilchrist, Stuart A.; Aulanier, Guillaume; Schmieder, Brigitte; Pariat, Etienne, E-mail: nj.lihui@pmo.ac.cn [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris-Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France)

    2016-05-20

    We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory /Atmospheric Imaging Assembly can be well reproduced from a Grad–Rubin nonlinear force-free field extrapolation method. Various inverse-S- and inverse-J-shaped magnetic field lines, which surround a coronal flux rope, coincide with the sigmoid as observed in different extreme-ultraviolet wavelengths, including its multithreaded curved ends. Also, the observed distribution of surface currents in the magnetic polarity where it was not prescribed is well reproduced. This validates our numerical implementation and setup of the Grad–Rubin method. The modeled double inverse-J-shaped quasi-separatrix layer (QSL) footprints match the observed flare ribbons during the rising phase of the flare, including their hooked parts. The spiral-like shape of the latter may be related to a complex pre-eruptive flux rope with more than one turn of twist, as obtained in the model. These ribbon-associated flux-rope QSL footprints are consistent with the new standard flare model in 3D, with the presence of a hyperbolic flux tube located below an inverse-teardrop-shaped coronal QSL. This is a new step forward forecasting the locations of reconnection and ribbons in solar flares and the geometrical properties of eruptive flux ropes.

  14. HOOKED FLARE RIBBONS AND FLUX-ROPE-RELATED QSL FOOTPRINTS

    International Nuclear Information System (INIS)

    Zhao, Jie; Li, Hui; Gilchrist, Stuart A.; Aulanier, Guillaume; Schmieder, Brigitte; Pariat, Etienne

    2016-01-01

    We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory /Atmospheric Imaging Assembly can be well reproduced from a Grad–Rubin nonlinear force-free field extrapolation method. Various inverse-S- and inverse-J-shaped magnetic field lines, which surround a coronal flux rope, coincide with the sigmoid as observed in different extreme-ultraviolet wavelengths, including its multithreaded curved ends. Also, the observed distribution of surface currents in the magnetic polarity where it was not prescribed is well reproduced. This validates our numerical implementation and setup of the Grad–Rubin method. The modeled double inverse-J-shaped quasi-separatrix layer (QSL) footprints match the observed flare ribbons during the rising phase of the flare, including their hooked parts. The spiral-like shape of the latter may be related to a complex pre-eruptive flux rope with more than one turn of twist, as obtained in the model. These ribbon-associated flux-rope QSL footprints are consistent with the new standard flare model in 3D, with the presence of a hyperbolic flux tube located below an inverse-teardrop-shaped coronal QSL. This is a new step forward forecasting the locations of reconnection and ribbons in solar flares and the geometrical properties of eruptive flux ropes.

  15. Giant Rapid X-ray Flares in Extragalactic Globular Clusters

    Science.gov (United States)

    Irwin, Jimmy

    2018-01-01

    There is only one known class of non-destructive, highly energetic astrophysical object in the Universe whose energy emission varies by more than a factor of 100 on time scales of less than a minute -- soft gamma repeaters/anomalous X-ray pulsars, whose flares are believed to be caused by the energy release from the cracking of a neutron star's surface by very strong magnetic fields. All other known violent, rapid explosions, including gamma-ray bursts and supernovae, are believed to destroy the object in the process. Here, we report the discovery of a second class of non-destructive, highly energetic rapidly flaring X-ray object located within two nearby galaxies with fundamentally different properties than soft gamma repeaters/anomalous X-ray pulsars. One source is located within a suspected globular cluster of the host galaxy and flared one time, while the other source is located in either a globular cluster of the host galaxy or the core of a stripped dwarf companion galaxy that flared on six occasions over a seven year time span. When not flaring, the sources appear as normal accreting neutron star or black hole X-ray binaries, indicating that the flare event does not significantly disrupt the host system. While the nature of these sources is still unclear, the discovery of these sources in decade-old archival Chandra X-ray Observatory data illustrates the under-utilization of X-ray timing as a means to discover new classes of explosive events in the Universe.

  16. The energetic relationship among geoeffective solar flares, associated CMEs and SEPs

    International Nuclear Information System (INIS)

    Bhatt Nipa J; Jain Rajmal; Awasthi Arun Kumar

    2013-01-01

    Major solar eruptions (flares, coronal mass ejections (CMEs) and solar energetic particles (SEPs)) strongly influence geospace and space weather. Currently, the mechanism of their influence on space weather is not well understood and requires a detailed study of the energetic relationship among these eruptive phenomena. From this perspective, we investigate 30 flares (observed by RHESSI), followed by weak to strong geomagnetic storms. Spectral analysis of these flares suggests a new power-law relationship (r ∼ 0.79) between the hard X-ray (HXR) spectral index (before flare-peak) and linear speed of the associated CME observed by LASCO/SOHO. For 12 flares which were followed by SEP enhancement near Earth, HXR and SEP spectral analysis reveals a new scaling law (r ∼ 0.9) between the hardest X-ray flare spectrum and the hardest SEP spectrum. Furthermore, a strong correlation is obtained between the linear speed of the CME and the hardest spectrum of the corresponding SEP event (r ∼ 0.96). We propose that the potentially geoeffective flare and associated CME and SEP are well-connected through a possible feedback mechanism, and should be regarded within the framework of a solar eruption. Owing to their space weather effects, these new results will help improve our current understanding of the Sun-Earth relationship, which is a major goal of research programs in heliophysics

  17. Solar Flares Observed with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

    Science.gov (United States)

    Holman, Gordon D.

    2004-01-01

    Solar flares are impressive examples of explosive energy release in unconfined, magnetized plasma. It is generally believed that the flare energy is derived from the coronal magnetic field. However, we have not been able to establish the specific energy release mechanism(s) or the relative partitioning of the released energy between heating, particle acceleration (electrons and ions), and mass motions. NASA's RHESSI Mission was designed to study the acceleration and evolution of electrons and ions in flares by observing the X-ray and gamma-ray emissions these energetic particles produce. This is accomplished through the combination of high-resolution spectroscopy and spectroscopic imaging, including the first images of flares in gamma rays. RHESSI has observed over 12,000 solar flares since its launch on February 5, 2002. I will demonstrate how we use the RHESSI spectra to deduce physical properties of accelerated electrons and hot plasma in flares. Using images to estimate volumes, w e typically find that the total energy in accelerated electrons is comparable to that in the thermal plasma. I will also present flare observations that provide strong support for the presence of magnetic reconnection in a large-scale, vertical current sheet in the solar corona. RHESSI observations such as these are allowing us to probe more deeply into the physics of solar flares.

  18. Variations of the Hβ-emission line during a large flare on UV Ceti

    International Nuclear Information System (INIS)

    Moffett, T.J.; Evans, D.S.; Ferland, G.

    1977-01-01

    Simultaneous high-speed photometry and photoelectric scanner observations of the Hβ-line were obtained for five flare events, one a major flare, on UV Ceti on 1975 January 6. The relative increase in the intensity of the Hβ-line during the large flare was much greater than the relative continuum rise as measured both by the scanner and by broad-band photometric observations. In Hβ the flare lasted nearly 30 times as long as in the continuum. Peak intensity in the Hβ-line occurred later than the continuum maximum. The possibility of using emission line observations to detect flare activity on early spectral-type stars (dK - dG) is discussed. Some speculations on the mechanism of flare production are indulged. (author)

  19. Decision 99-27 application 1029022 - Petro-Canada Oil and Gas application to install compressors at the Wilson Creek gas plant and at LSD 3-19-43-4 W5M, Wilson Creek Field

    International Nuclear Information System (INIS)

    1999-11-01

    Petro-Canada Oil and Gas applied to the Alberta Energy and Utilities Board (EUB) for approval to add two new compressors at the existing Wilson Creek sour gas processing facility, and to construct and operate a new sour gas compressor station in Alberta. The application was made pursuant to Section 26 (1)(b) of the Oil and Gas Conservation Act and Sections 7.001, 9.020, and 15.050 of the Oil and Gas Conservation Regulations. The applications and interventions were considered at a hearing at the Last West Hall, Rimbley, Alberta, commencing 7 April 1999. The issues concerning the applications were: the need for and location of the compressors, plant life, emissions, sulphur recovery, and noise. Petro-Canada will proceed with its commitment to local landowners to install and commission a sulphur recovery unit within 16 months of the date of this report. The sulphur recovery capability of the facility will meet guidelines defined in IL 88-13 for new sour gas plants based on either the current or an acceptable maximum daily inlet sulphur rate. Continuous-vent gas streams, including glycol regenerator, produced-water tank, and hydrocarbon condensate tank vents, at both the 3-29 compressor and at the Wilson Creek plant site will be burned in a flare or incinerator. Flare stacks at the 3-19 compressor site will be equipped with a suitable pilot and automatic igniter. The Wilson Creek plant flare system will be equipped with a suitable pilot, as well as automatic igniter and/or flame failure detection system. Petro-Canada will implement local ambient air quality monitoring and sound level monitoring consistent with its commitments to local landowners and regulatory requirements

  20. Discovery of decaHz flaring in SAX J1808.4-3658

    NARCIS (Netherlands)

    Bult, P.

    2014-01-01

    We report on the discovery of strong decaHz flaring in the early decay of two out of five outbursts of the accreting millisecond X-ray pulsar SAX J1808.4-3658. The decaHz flaring switches on and, after ~3 days, off again, on a time scale of 1-2 hours. When the flaring is present, the total 0.05-10

  1. Bright x-ray flares in gamma-ray burst afterglows.

    Science.gov (United States)

    Burrows, D N; Romano, P; Falcone, A; Kobayashi, S; Zhang, B; Moretti, A; O'brien, P T; Goad, M R; Campana, S; Page, K L; Angelini, L; Barthelmy, S; Beardmore, A P; Capalbi, M; Chincarini, G; Cummings, J; Cusumano, G; Fox, D; Giommi, P; Hill, J E; Kennea, J A; Krimm, H; Mangano, V; Marshall, F; Mészáros, P; Morris, D C; Nousek, J A; Osborne, J P; Pagani, C; Perri, M; Tagliaferri, G; Wells, A A; Woosley, S; Gehrels, N

    2005-09-16

    Gamma-ray burst (GRB) afterglows have provided important clues to the nature of these massive explosive events, providing direct information on the nearby environment and indirect information on the central engine that powers the burst. We report the discovery of two bright x-ray flares in GRB afterglows, including a giant flare comparable in total energy to the burst itself, each peaking minutes after the burst. These strong, rapid x-ray flares imply that the central engines of the bursts have long periods of activity, with strong internal shocks continuing for hundreds of seconds after the gamma-ray emission has ended.

  2. Radiolytic gas formation in high-level liquid waste solutions

    International Nuclear Information System (INIS)

    Brodda, B.-G.; Dix, Siegfried; Merz, E.R.

    1989-01-01

    High-level fission product waste solutions originating from the first-cycle raffinate stream of spent fast breeder reactor fuel reprocessing have been investigated gas chromatographically for their radiolytic and chemical gas production. The solutions showed considerable formation of hydrogen, carbon dioxide and dinitrogen oxide, whereas atmospheric oxygen was consumed completely within a short time. In particular, carbon dioxide resulted from the radiolytic degradation of entrained organic solvent. After nearly complete degradation of the organic solvent, the influence of hydrazine and nitrogen dioxide on hydrogen formation was investigated. Hydrazinium hydroxide led to the formation of dinitrogen oxide and nitrogen. After 60 d, the concentration of dinitrogen oxide had reduced to zero, whereas the amount of nitrogen formed had reached a maximum. This may be explained by simultaneous chemical and radiolytic reactions leading to the formation of dinitrogen oxide and nitrogen and photolytic fission of dinitrogen oxide. Addition of sodium nitrite resulted in the rapid formation of dinitrogen oxide. The rate of hydrogen production was not changed significantly after the addition of hydrazine or nitrite. The results indicate that under normal operating conditions no dangerous hydrogen radiolysis yields should develop in the course of reprocessing and high-level liquid waste tank storage. Organic entrainment may lead to enhanced radiolytic decomposition and thus to considerable hydrogen production rates and pressure build-up in closed systems. (author)

  3. Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares

    Science.gov (United States)

    McLaughlin, J. A.; Nakariakov, V. M.; Dominique, M.; Jelínek, P.; Takasao, S.

    2018-02-01

    Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic pulsations (QPPs), to emphasise that they often contain apparent amplitude and period modulation. We review the current understanding of quasi-periodic pulsations in solar and stellar flares. In particular, we focus on the possible physical mechanisms, with an emphasis on the underlying physics that generates the resultant range of periodicities. These physical mechanisms include MHD oscillations, self-oscillatory mechanisms, oscillatory reconnection/reconnection reversal, wave-driven reconnection, two loop coalescence, MHD flow over-stability, the equivalent LCR-contour mechanism, and thermal-dynamical cycles. We also provide a histogram of all QPP events published in the literature at this time. The occurrence of QPPs puts additional constraints on the interpretation and understanding of the fundamental processes operating in flares, e.g. magnetic energy liberation and particle acceleration. Therefore, a full understanding of QPPs is essential in order to work towards an integrated model of solar and stellar flares.

  4. A COLD FLARE WITH DELAYED HEATING

    International Nuclear Information System (INIS)

    Fleishman, Gregory D.; Pal'shin, Valentin D.; Lysenko, Alexandra L.; Meshalkina, Natalia; Kashapova, Larisa K.; Altyntsev, Alexander T.

    2016-01-01

    Recently, a number of peculiar flares have been reported that demonstrate significant nonthermal particle signatures with low, if any, thermal emission, which implies a close association of the observed emission with the primary energy release/electron acceleration region. This paper presents a flare that appears “cold” at the impulsive phase, while displaying delayed heating later on. Using hard X-ray data from Konus- Wind , microwave observations by SSRT, RSTN, NoRH, and NoRP, context observations, and three-dimensional modeling, we study the energy release, particle acceleration, and transport, and the relationships between the nonthermal and thermal signatures. The flaring process is found to involve the interaction between a small loop and a big loop with the accelerated particles divided roughly equally between them. Precipitation of the electrons from the small loop produced only a weak thermal response because the loop volume was small, while the electrons trapped in the big loop lost most of their energy in the coronal part of the loop, which resulted in coronal plasma heating but no or only weak chromospheric evaporation, and thus unusually weak soft X-ray emission. The energy losses of the fast electrons in the big tenuous loop were slow, which resulted in the observed delay of the plasma heating. We determined that the impulsively accelerated electron population had a beamed angular distribution in the direction of the electric force along the magnetic field of the small loop. The accelerated particle transport in the big loop was primarily mediated by turbulent waves, which is similar to other reported cold flares.

  5. Physics of Coupled CME and Flare Systems

    Science.gov (United States)

    2016-12-21

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0162 TR-2016-0162 PHYSICS OF COUPLED CME AND FLARE SYSTEMS K. S. Balasubramaniam, et al. 21 December 2016 Final...30 Sep 2016 4. TITLE AND SUBTITLE Physics of Coupled CME and Flare Systems 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F...objectives for this task were: (i) derive measureable physical properties and discernible structural circumstances in solar active regions that

  6. Magnetic Properties of Solar Active Regions that Govern Large Solar Flares and Eruptions

    Science.gov (United States)

    Toriumi, Shin; Schrijver, Carolus J.; Harra, Louise; Hudson, Hugh S.; Nagashima, Kaori

    2017-08-01

    Strong flares and CMEs are often produced from active regions (ARs). In order to better understand the magnetic properties and evolutions of such ARs, we conducted statistical investigations on the SDO/HMI and AIA data of all flare events with GOES levels >M5.0 within 45 deg from the disk center for 6 years from May 2010 (from the beginning to the declining phase of solar cycle 24). Out of the total of 51 flares from 29 ARs, more than 80% have delta-sunspots and about 15% violate Hale’s polarity rule. We obtained several key findings including (1) the flare duration is linearly proportional to the separation of the flare ribbons (i.e., scale of reconnecting magnetic fields) and (2) CME-eruptive events have smaller sunspot areas. Depending on the magnetic properties, flaring ARs can be categorized into several groups, such as spot-spot, in which a highly-sheared polarity inversion line is formed between two large sunspots, and spot-satellite, where a newly-emerging flux next to a mature sunspot triggers a compact flare event. These results point to the possibility that magnetic structures of the ARs determine the characteristics of flares and CMEs. In the presentation, we will also show new results from the systematic flux emergence simulations of delta-sunspot formation and discuss the evolution processes of flaring ARs.

  7. Stellar flare oscillations: evidence for oscillatory reconnection and evolution of MHD modes

    Science.gov (United States)

    Doyle, J. G.; Shetye, J.; Antonova, A. E.; Kolotkov, D. Y.; Srivastava, A. K.; Stangalini, M.; Gupta, G. R.; Avramova, A.; Mathioudakis, M.

    2018-04-01

    Here, we report on the detection of a range of quasi-periodic pulsations (20-120 s; QPPs) observed during flaring activity of several magnetically active dMe stars, namely AF Psc, CR Dra, GJ 3685A, Gl 65, SDSS J084425.9+513830, and SDSS J144738.47+035312.1 in the GALEX NUV filter. Based on a solar analogy, this work suggests that many of these flares may be triggered by external drivers creating a periodic reconnection in the flare current sheet or an impulsive energy release giving rise to an avalanche of periodic bursts that occur at time intervals that correspond to the detected periods, thus generating QPPs in their rising and peak phases. Some of these flares also show fast QPPs in their decay phase, indicating the presence of fast sausage mode oscillations either driven externally by periodic reconnection or intrinsically in the post-flare loop system during the flare energy release.

  8. HIGH-ENERGY NEUTRINOS FROM RECENT BLAZAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Halzen, Francis; Kheirandish, Ali [Wisconsin IceCube Particle Astrophysics Center and Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

    2016-11-01

    The energy density of cosmic neutrinos measured by IceCube matches the one observed by Fermi in extragalactic photons that predominantly originate in blazars. This has inspired attempts to match Fermi sources with IceCube neutrinos. A spatial association combined with a coincidence in time with a flaring source may represent a smoking gun for the origin of the IceCube flux. In 2015 June, the Fermi Large Area Telescope observed an intense flare from blazar 3C 279 that exceeded the steady flux of the source by a factor of 40 for the duration of a day. We show that IceCube is likely to observe neutrinos, if indeed hadronic in origin, in data that are still blinded at this time. We also discuss other opportunities for coincident observations that include a recent flare from blazar 1ES 1959+650 that previously produced an intriguing coincidence with AMANDA observations.

  9. Thermodynamic Spectrum of Solar Flares Based on SDO/EVE Observations: Techniques and First Results

    Science.gov (United States)

    Wang, Yuming; Zhou, Zhenjun; Zhang, Jie; Liu, Kai; Liu, Rui; Shen, Chenglong; Chamberlin, Phillip C.

    2016-01-01

    The Solar Dynamics Observatory (SDO)/EUV Variability Experiment (EVE) provides rich information on the thermodynamic processes of solar activities, particularly on solar flares. Here, we develop a method to construct thermodynamic spectrum (TDS) charts based on the EVE spectral lines. This tool could potentially be useful for extreme ultraviolet (EUV) astronomy to learn about the eruptive activities on distant astronomical objects. Through several cases, we illustrate what we can learn from the TDS charts. Furthermore, we apply the TDS method to 74 flares equal to or greater than the M5.0 class, and reach the following statistical results. First, EUV peaks are always behind the soft X-ray (SXR) peaks and stronger flares tend to have faster cooling rates. There is a power-law correlation between the peak delay times and the cooling rates, suggesting a coherent cooling process of flares from SXR to EUV emissions. Second, there are two distinct temperature drift patterns, called Type I and Type II. For Type I flares, the enhanced emission drifts from high to low temperature like a quadrilateral, whereas for Type II flares the drift pattern looks like a triangle. Statistical analysis suggests that Type II flares are more impulsive than Type I flares. Third, for late-phase flares, the peak intensity ratio of the late phase to the main phase is roughly correlated with the flare class, and the flares with a strong late phase are all confined. We believe that the re-deposition of the energy carried by a flux rope, which unsuccessfully erupts out, into thermal emissions is responsible for the strong late phase found in a confined flare. Furthermore, we show the signatures of the flare thermodynamic process in the chromosphere and transition region in the TDS charts. These results provide new clues to advance our understanding of the thermodynamic processes of solar flares and associated solar eruptions, e.g., coronal mass ejections.

  10. THERMODYNAMIC SPECTRUM OF SOLAR FLARES BASED ON SDO/EVE OBSERVATIONS: TECHNIQUES AND FIRST RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuming; Zhou, Zhenjun; Liu, Kai; Liu, Rui; Shen, Chenglong [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Jie [School of Physics, Astronomy and Computational Sciences, George Mason University, 4400 University Drive, MSN 6A2, Fairfax, VA 22030 (United States); Chamberlin, Phillip C., E-mail: ymwang@ustc.edu.cn [Solar Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-03-15

    The Solar Dynamics Observatory (SDO)/EUV Variability Experiment (EVE) provides rich information on the thermodynamic processes of solar activities, particularly on solar flares. Here, we develop a method to construct thermodynamic spectrum (TDS) charts based on the EVE spectral lines. This tool could potentially be useful for extreme ultraviolet (EUV) astronomy to learn about the eruptive activities on distant astronomical objects. Through several cases, we illustrate what we can learn from the TDS charts. Furthermore, we apply the TDS method to 74 flares equal to or greater than the M5.0 class, and reach the following statistical results. First, EUV peaks are always behind the soft X-ray (SXR) peaks and stronger flares tend to have faster cooling rates. There is a power-law correlation between the peak delay times and the cooling rates, suggesting a coherent cooling process of flares from SXR to EUV emissions. Second, there are two distinct temperature drift patterns, called Type I and Type II. For Type I flares, the enhanced emission drifts from high to low temperature like a quadrilateral, whereas for Type II flares the drift pattern looks like a triangle. Statistical analysis suggests that Type II flares are more impulsive than Type I flares. Third, for late-phase flares, the peak intensity ratio of the late phase to the main phase is roughly correlated with the flare class, and the flares with a strong late phase are all confined. We believe that the re-deposition of the energy carried by a flux rope, which unsuccessfully erupts out, into thermal emissions is responsible for the strong late phase found in a confined flare. Furthermore, we show the signatures of the flare thermodynamic process in the chromosphere and transition region in the TDS charts. These results provide new clues to advance our understanding of the thermodynamic processes of solar flares and associated solar eruptions, e.g., coronal mass ejections.

  11. Intralesional triamcinolone for flares of hidradenitis suppurativa (HS)

    DEFF Research Database (Denmark)

    Riis, Peter Theut; Boer, Jurr; Prens, Errol P

    2016-01-01

    (triamcinolone acetonide 10 mg/mL) in the management of acute flares in HS. METHODS: This was a prospective case series evaluating the effect of intralesional corticosteroids for alleviation of acute flares in HS. Physician- and patient-reported outcomes were noted. RESULTS: Significant reductions in physician......-assessed erythema (median score from 2-1, P edema (median score from 2-1, P

  12. The classification of flaring states of blazars

    Science.gov (United States)

    Resconi, E.; Franco, D.; Gross, A.; Costamante, L.; Flaccomio, E.

    2009-08-01

    Aims: The time evolution of the electromagnetic emission from blazars, in particular high-frequency peaked sources (HBLs), displays irregular activity that has not yet been understood. In this work we report a methodology capable of characterizing the time behavior of these variable objects. Methods: The maximum likelihood blocks (MLBs) is a model-independent estimator that subdivides the light curve into time blocks, whose length and amplitude are compatible with states of constant emission rate of the observed source. The MLBs yield the statistical significance in the rate variations and strongly suppresses the noise fluctuations in the light curves. We applied the MLBs for the first time on the long term X-ray light curves (RXTE/ASM) of Mkn 421, Mkn 501, 1ES 1959+650, and 1ES 2155-304, more than 10 years of observational data (1996-2007). Using the MLBs interpretation of RXTE/ASM data, the integrated time flux distribution is determined for each single source considered. We identify in these distributions the characteristic level, as well as the flaring states of the blazars. Results: All the distributions show a significant component at negative flux values, most probably caused by an uncertainty in the background subtraction and by intrinsic fluctuations of RXTE/ASM. This effect concerns in particular short time observations. To quantify the probability that the intrinsic fluctuations give rise to a false identification of a flare, we study a population of very faint sources and their integrated time-flux distribution. We determine duty cycle or fraction of time a source spent in the flaring state of the source Mkn 421, Mkn 501, 1ES 1959+650 and 1ES 2155-304. Moreover, we study the random coincidences between flares and generic sporadic events such as high-energy neutrinos or flares in other wavelengths.

  13. Prediction of gas hold-up for alcohol solutions in a draft-tube bubble column

    Directory of Open Access Journals (Sweden)

    Albijanić Boris V.

    2006-01-01

    Full Text Available This paper deals with the prediction of the overall gas hold-up (εg, in the diluted solutions of C -C alcohols in draft - tube bubble column, by applying several newly proposed correlations and some of the well-known equations. Experiments were carried out in a column, consisting of two coaxial glass tubes, with a single sparger. Gas phase was air, while the liquid phases were aqueous solutions of alcohols, in concentrations of 0.5% w/w and 1% w/w. Overall gas hold-up was determined by applying volume expansion technique. The following order for εg values was observed: water < methanol < ethanol < n-propanol < n-butanol. Concentration of the applied alcohol appeared to be less significant than the .sort of alcohol itself. The best newly proposed correlation enables predicting of our experimental data with the average square deviation of empirical formula: s2=0.58 E-04.

  14. MR Persei - A new rotating, spotted flare star

    Science.gov (United States)

    Honeycutt, R. K.; Turner, G. W.; Vesper, D. N.; Schlegel, E. M.

    1992-01-01

    Spectroscopy and photometry are used to show that MR Persei, an object originally classified as a dwarf nova, is in fact a flare star. The automated CCD photometry consists of sequences of exposures within a single night as well as long-term photometry over a five-month interval. One sequence shows a 30-min flare, accompanied by post-flare 'dips'. A 0.2 mag variation with a period of about one-half day is also seen in this sequence. The long-term photometry is used to refine the period to 0.45483 d, which we attribute to the rotation of a spotted star. Evidence for membership of MR Per in the young Alpha Per cluster is considered, and found to be inconclusive.

  15. A Study of Sympathetic Flaring Using a Full-Sun Event Catalog

    Science.gov (United States)

    Higgins, P. A.; Schrijver, C. J.; Title, A. M.; Bloomfield, D.; Gallagher, P.

    2013-12-01

    There has been a trove of papers published on the statistics of flare occurrence. These studies are trying to answer the question of whether or not subsequent solar flares are related. The majority of these works have not included both flare location information and the physical properties of the regions responsible for the eruptions, and none have taken advantage of full-Sun event coverage. Now that SDO/AIA is available and the STEREO spacecraft have progressed past 90 degrees from Earth's heliographic longitude, this new information is available to us. This work aims to quantify how common sympathetic events are, and how important they are in the forecasting of solar flares. A 3D plot of detected and clustered flare events for a full solar rotation, including the Valentine's Day Event of 2011. A full-Sun image in the EUV (304A) including both STEREO view points and AIA. The GOES X-ray light curves during the February period of 2011 are shown in the bottom panel. Detected flare events are indicated by the green dashed lines and the time stamp of this image is denoted by the red line.

  16. Are Complex Magnetic Field Structures Responsible for the Confined X-class Flares in Super Active Region 12192?

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun; Li, Ting; Chen, Huadong, E-mail: zjun@nao.cas.cn, E-mail: hdchen@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2017-08-10

    From 2014 October 19 to 27, six X-class flares occurred in super active region (AR) 12192. They were all confined flares and were not followed by coronal mass ejections. To examine the structures of the four flares close to the solar disk center from October 22 to 26, we firstly employ composite triple-time images in each flare process to display the stratified structure of these flare loops. The loop structures of each flare in both the lower (171 Å) and higher (131 Å) temperature channels are complex, e.g., the flare loops rooting at flare ribbons are sheared or twisted (enwound) together, and the complex structures were not destroyed during the flares. For the first flare, although the flare loop system appears as a spindle shape, we can estimate its structures from observations, with lengths ranging from 130 to 300 Mm, heights from 65 to 150 Mm, widths at the middle part of the spindle from 40 to 100 Mm, and shear angles from 16° to 90°. Moreover, the flare ribbons display irregular movements, such as the left ribbon fragments of the flare on October 22 sweeping a small region repeatedly, and both ribbons of the flare on October 26 moved along the same direction instead of separating from each other. These irregular movements also imply that the corresponding flare loops are complex, e.g., several sets of flare loops are twisted together. Although previous studies have suggested that the background magnetic fields prevent confined flares from erupting,based on these observations, we suggest that complex flare loop structures may be responsible for these confined flares.

  17. Center-to-Limb Variability of Hot Coronal EUV Emissions During Solar Flares

    Science.gov (United States)

    Thiemann, E. M. B.; Chamberlin, P. C.; Eparvier, F. G.; Epp, L.

    2018-02-01

    It is generally accepted that densities of quiet-Sun and active region plasma are sufficiently low to justify the optically thin approximation, and this is commonly used in the analysis of line emissions from plasma in the solar corona. However, the densities of solar flare loops are substantially higher, compromising the optically thin approximation. This study begins with a radiative transfer model that uses typical solar flare densities and geometries to show that hot coronal emission lines are not generally optically thin. Furthermore, the model demonstrates that the observed line intensity should exhibit center-to-limb variability (CTLV), with flares observed near the limb being dimmer than those occurring near disk center. The model predictions are validated with an analysis of over 200 flares observed by the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO), which uses six lines, with peak formation temperatures between 8.9 and 15.8 MK, to show that limb flares are systematically dimmer than disk-center flares. The data are then used to show that the electron column density along the line of sight typically increases by 1.76 × 10^{19} cm^{-2} for limb flares over the disk-center flare value. It is shown that the CTLV of hot coronal emissions reduces the amount of ionizing radiation propagating into the solar system, and it changes the relative intensities of lines and bands commonly used for spectral analysis.

  18. Lower atmosphere of solar flares; Proceedings of the Solar Maximum Mission Symposium, Sunspot, NM, Aug. 20-24, 1985

    International Nuclear Information System (INIS)

    Neidig, D.F.

    1986-01-01

    The topics discussed by the present conference encompass the chromospheric flare phenomenon, white light flares, UV emission and the flare transition region, the flare corona and high energy emissions, stellar flares, and flare energy release and transport. Attention is given to radiative shocks and condensation in flares, impulsive brightening of H-alpha flare points, the structure and response of the chromosphere to radiation backwarming during solar flares, the interpretation of continuum emissions in white light flares, and the radiation properties of solar plasmas. Also discussed are EUV images of a solar flare and C III intensity, an active region survey in H-alpha and X-rays, dynamic thermal plasma conditions in large flares, the evolution of the flare mechanism in dwarf stars, the evidence concerning electron beams in solar flares, the energetics of the nonlinear tearing mode, macroscopic electric fields during two-ribbon flares, and the low temperature signatures of energetic particles

  19. The Dependence of Solar Flare Limb Darkening on Emission Peak Formation Temperature

    Science.gov (United States)

    Thiemann, Edward; Epp, Luke; Eparvier, Francis; Chamberlin, Phillip C.

    2017-08-01

    Solar limb effects are local brightening or darkening of an emission that depend on where in the Sun's atmosphere it forms. Near the solar limb, optically thick (thin) emissions will darken (brighten) as the column of absorbers (emitters) along the line-of-sight increases. Note that in limb brightening, emission sources are re-arranged whereas in limb darkening they are obscured. Thus, only limb darkening is expected to occur in disk integrated observations. Limb darkening also results in center-to-limb variations of disk-integrated solar flare spectra, with important consequences for how planetary atmospheres are affected by flares. Flares are typically characterized by their flux in the optically thin 0.1-0.8 nm band measured by the X-ray Sensor (XRS) on board the Geostationary Operational Environmental Satellite (GOES). On the other hand, Extreme Ultraviolet (EUV) line emissions can limb darken because they are sensitive to resonant scattering, resulting in a flare's location on the solar disk controlling the amount of ionizing radiation that reaches a planet. For example, an X-class flare originating from disk center may significantly heat a planet's thermosphere, whereas the same flare originating near the limb may have no effect because much of the effective emissions are scattered in the solar corona.To advance the relatively poor understanding of flare limb darkening, we use over 300 M-class or larger flares observed by the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) to characterize limb darkening as a function of emission peak formation temperature, Tf. For hot coronal emissions (Tf>2 MK), these results show a linear relationship between the degree of limb darkening and Tf where lines with Tf=2 MK darken approximately 7 times more than lines with Tf=16 MK. Because the extent of limb darkening is dependent on the height of the source plasma, we use simple Beer-Lambert radiative transfer analysis to interpret these results

  20. Brief Report: Validation of a Definition of Flare in Patients With Established Gout.

    Science.gov (United States)

    Gaffo, Angelo L; Dalbeth, Nicola; Saag, Kenneth G; Singh, Jasvinder A; Rahn, Elizabeth J; Mudano, Amy S; Chen, Yi-Hsing; Lin, Ching-Tsai; Bourke, Sandra; Louthrenoo, Worawit; Vazquez-Mellado, Janitzia; Hernández-Llinas, Hansel; Neogi, Tuhina; Vargas-Santos, Ana Beatriz; da Rocha Castelar-Pinheiro, Geraldo; Amorim, Rodrigo B C; Uhlig, Till; Hammer, Hilde B; Eliseev, Maxim; Perez-Ruiz, Fernando; Cavagna, Lorenzo; McCarthy, Geraldine M; Stamp, Lisa K; Gerritsen, Martijn; Fana, Viktoria; Sivera, Francisca; Taylor, William

    2018-03-01

    To perform external validation of a provisional definition of disease flare in patients with gout. Five hundred nine patients with gout were enrolled in a cross-sectional study during a routine clinical care visit at 17 international sites. Data were collected to classify patients as experiencing or not experiencing a gout flare, according to a provisional definition. A local expert rheumatologist performed the final independent adjudication of gout flare status. Sensitivity, specificity, predictive values, and receiver operating characteristic (ROC) curves were used to determine the diagnostic performance of gout flare definitions. The mean ± SD age of the patients was 57.5 ± 13.9 years, and 89% were male. The definition requiring fulfillment of at least 3 of 4 criteria (patient-defined gout flare, pain at rest score of >3 on a 0-10-point numerical rating scale, presence of at least 1 swollen joint, and presence of at least 1 warm joint) was 85% sensitive and 95% specific in confirming the presence of a gout flare, with an accuracy of 92%. The ROC area under the curve was 0.97. The definition based on a classification and regression tree algorithm (entry point, pain at rest score >3, followed by patient-defined flare "yes") was 73% sensitive and 96% specific. The definition of gout flare that requires fulfillment of at least 3 of 4 patient-reported criteria is now validated to be sensitive, specific, and accurate for gout flares, as demonstrated using an independent large international patient sample. The availability of a validated gout flare definition will improve the ascertainment of an important clinical outcome in studies of gout. © 2017, American College of Rheumatology.

  1. Spectropolarimetric Inversions of the Ca II 8542 Å Line in an M-class Solar Flare

    Science.gov (United States)

    Kuridze, D.; Henriques, V. M. J.; Mathioudakis, M.; Rouppe van der Voort, L.; de la Cruz Rodríguez, J.; Carlsson, M.

    2018-06-01

    We study the M1.9-class solar flare SOL2015-09-27T10:40 UT using high-resolution full Stokes imaging spectropolarimetry of the Ca II 8542 Å line obtained with the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope. Spectropolarimetric inversions using the non-LTE code NICOLE are used to construct semiempirical models of the flaring atmosphere to investigate the structure and evolution of the flare temperature and magnetic field. A comparison of the temperature stratification in flaring and nonflaring areas reveals strong heating of the flare ribbon during the flare peak. The polarization signals of the ribbon in the chromosphere during the flare maximum become stronger when compared to its surroundings and to pre- and post-flare profiles. Furthermore, a comparison of the response functions to perturbations in the line-of-sight magnetic field and temperature in flaring and nonflaring atmospheres shows that during the flare, the Ca II 8542 Å line is more sensitive to the lower atmosphere where the magnetic field is expected to be stronger. The chromospheric magnetic field was also determined with the weak-field approximation, which led to results similar to those obtained with the NICOLE inversions.

  2. A Novel Forecasting System for Solar Particle Events and Flares (FORSPEF)

    International Nuclear Information System (INIS)

    Papaioannou, A; Anastasiadis, A; Sandberg, I; Tsiropoula, G; Tziotziou, K; Georgoulis, M K; Jiggens, P; Hilgers, A

    2015-01-01

    Solar Energetic Particles (SEPs) result from intense solar eruptive events such as solar flares and coronal mass ejections (CMEs) and pose a significant threat for both personnel and infrastructure in space conditions. In this work, we present FORSPEF (Forecasting Solar Particle Events and Flares), a novel dual system, designed to perform forecasting of SEPs based on forecasting of solar flares, as well as independent SEP nowcasting. An overview of flare and SEP forecasting methods of choice is presented. Concerning SEP events, we make use for the first time of the newly re-calibrated GOES proton data within the energy range 6.0-243 MeV and we build our statistics on an extensive time interval that includes roughly 3 solar cycles (1984-2013). A new comprehensive catalogue of SEP events based on these data has been compiled including solar associations in terms of flare (magnitude, location) and CME (width, velocity) characteristics. (paper)

  3. New mathematical method for the solution of gas-gas equilibria with special application to HTGR primary-coolant environments

    International Nuclear Information System (INIS)

    Bongartz, K.

    1983-07-01

    A new mathematical method and corresponding computer program have been developed that provide a general method for the numerical solution of an equilibrium problem involving the chemical interactions of gaseous species. The method and computer code were developed to calculate the equilibrium concentrations of impurity gases, such as CO, CO 2 , H 2 , H 2 O, CH 4 , and O 2 , which may be approached as the result of gaseous chemical reactions occurring within the hot primary coolant helium of a high-temperature gas-cooled reactor (HTGR). The method, however, can be applied to any gas mixture

  4. Transition Region Emission and the Energy Input to Thermal Plasma in Solar Flares

    Science.gov (United States)

    Holman, Gordon D.; Holman, Gordon D.; Dennis, Brian R.; Haga, Leah; Raymond, John C.; Panasyuk, Alexander

    2005-01-01

    Understanding the energetics of solar flares depends on obtaining reliable determinations of the energy input to flare plasma. X-ray observations of the thermal bremsstrahlung from hot flare plasma provide temperatures and emission measures which, along with estimates of the plasma volume, allow the energy content of this hot plasma to be computed. However, if thermal energy losses are significant or if significant energy goes directly into cooler plasma, this is only a lower limit on the total energy injected into thermal plasma during the flare. We use SOHO UVCS observations of O VI flare emission scattered by coronal O VI ions to deduce the flare emission at transition region temperatures between 100,000 K and 1 MK for the 2002 July 23 and other flares. We find that the radiated energy at these temperatures significantly increases the deduced energy input to the thermal plasma, but by an amount that is less than the uncertainty in the computed energies. Comparisons of computed thermal and nonthermal electron energies deduced from RHESSI, GOES, and UVCS are shown.

  5. Utilization of the waste gases from a petroleum refinery as fuel

    International Nuclear Information System (INIS)

    Torres Contreras, Jose Francisco

    2012-01-01

    The fuels waste gases that are burned in a flare stack were proposed as an alternative for its utilization. The current operation of the flare stack system of a petroleum refinery was analyzed. The historical information of the equipment and original design of the same was used. From the calculations that were performed, it is expected that the delivered heat for the flare gases approaching to 65 MJ/M 3 , so it would be an effective fuel for be used in furnaces and boilers. A new flare stack system and a system for recovery of the waste gases of process is proposed. The new flare stack system must have a liquid separator of 2,3 meters of diameter, a length of 6,4 meters and a capacity of 26,1 cubic meters. The velocity of the gas to the exit of the separator has been of 80,7 m/s. The liquid hydrocarbon flow that has exited the separator has been of 71 m 3 /h, with a speed of 0,91 m/s and a pump of 2,75 HP is required. The liquid seal of flare stack systems must have a minimum height of 1,05 m. The gas recovery system to burn in the flare stack should be located between the liquid separator and liquid seal of the flare stack systems. For an average consumption of 150 m 3 /h of fuel gas for furnaces and boilers, the gas recovery system must have with a compressor of 4,75 HP, a liquid separator of 50 m 3 and a pump of 2,50 HP. The gas recovery system has had with an absorber of 7 plates for washing of the stream acid gas with MEA, at 40 degrees celsius and an pressure of operating of 67 kPa, and a flow of 55,88 kg/h at amine solution. The flare gas flow has been recommended to be analyzed chemically, as well as the measurement of the flow of gas streams plant consumption and gases flare. A technical-economic feasibility study of the process should be realized. (author) [es

  6. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Science.gov (United States)

    Yu, Z. X.; Ma, Y. Z.; Zhao, Y. L.; Huang, J. B.; Wang, W. Z.; Moliere, M.; Liao, H. L.

    2017-08-01

    Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P(002). It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the "first principle calculation method" and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have favorable performances to be used as sensitive layer in gas sensing applications.

  7. The Effect of Magnetic Topology on the Escape of Flare Particles

    Science.gov (United States)

    Antiochos, S. K.; Masson, S.; DeVore, C. R.

    2012-01-01

    Magnetic reconnection in the solar atmosphere is believed to be the driver of most solar explosive phenomena. Therefore, the topology of the coronal magnetic field is central to understanding the solar drivers of space weather. Of particular importance to space weather are the impulsive Solar Energetic particles that are associated with some CME/eruptive flare events. Observationally, the magnetic configuration of active regions where solar eruptions originate appears to agree with the standard eruptive flare model. According to this model, particles accelerated at the flare reconnection site should remain trapped in the corona and the ejected plasmoid. However, flare-accelerated particles frequently reach the Earth long before the CME does. We present a model that may account for the injection of energetic particles onto open magnetic flux tubes connecting to the Earth. Our model is based on the well-known 2.5D breakout topology, which has a coronal null point (null line) and a four-flux system. A key new addition, however, is that we include an isothermal solar wind with open-flux regions. Depending on the location of the open flux with respect to the null point, we find that the flare reconnection can consist of two distinct phases. At first, the flare reconnection involves only closed field, but if the eruption occurs close to the open field, we find a second phase involving interchange reconnection between open and closed. We argue that this second reconnection episode is responsible for the injection of flare-accelerated particles into the interplanetary medium. We will report on our recent work toward understanding how flare particles escape to the heliosphere. This work uses high-resolution 2.5D MHD numerical simulations performed with the Adaptively Refined MHD Solver (ARMS).

  8. Solar Features - Solar Flares - Patrol

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The H-alpha Flare Patrol identifies time periods each day when the sun is being continuously monitored by select ground-based solar observatories.

  9. Planetary Protection: X-ray Super-Flares Aid Formation of "Solar Systems"

    Science.gov (United States)

    2005-05-01

    New results from NASA's Chandra X-ray Observatory imply that X-ray super-flares torched the young Solar System. Such flares likely affected the planet-forming disk around the early Sun, and may have enhanced the survival chances of Earth. By focusing on the Orion Nebula almost continuously for 13 days, a team of scientists used Chandra to obtain the deepest X-ray observation ever taken of this or any star cluster. The Orion Nebula is the nearest rich stellar nursery, located just 1,500 light years away. These data provide an unparalleled view of 1400 young stars, 30 of which are prototypes of the early Sun. The scientists discovered that these young suns erupt in enormous flares that dwarf - in energy, size, and frequency -- anything seen from the Sun today. Illustration of Large Flares Illustration of Large Flares "We don't have a time machine to see how the young Sun behaved, but the next best thing is to observe Sun-like stars in Orion," said Scott Wolk of Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "We are getting a unique look at stars between one and 10 million years old - a time when planets form." A key result is that the more violent stars produce flares that are a hundred times as energetic as the more docile ones. This difference may specifically affect the fate of planets that are relatively small and rocky, like the Earth. "Big X-ray flares could lead to planetary systems like ours where Earth is a safe distance from the Sun," said Eric Feigelson of Penn State University in University Park, and principal investigator for the international Chandra Orion Ultradeep Project. "Stars with smaller flares, on the other hand, might end up with Earth-like planets plummeting into the star." Animation of X-ray Flares from a Young Sun Animation of X-ray Flares from a "Young Sun" According to recent theoretical work, X-ray flares can create turbulence when they strike planet-forming disks, and this affects the position of rocky planets as they

  10. Detecting Solar Neutrino Flare in Megaton and km3 detectors

    International Nuclear Information System (INIS)

    Fargion, Daniele; Di Giacomo, Paola

    2009-01-01

    To foresee a solar flare neutrino signal we infer its upper and lower bound. The upper bound was derived since a few years by general energy equipartition arguments on observed solar particle flare. The lower bound, the most compelling one for any guarantee neutrino signal, is derived by most recent records of hard Gamma bump due to solar flare on January 2005 (by neutral pion decay). Because neutral and charged pions (made by hadron scattering in the flare) are born on the same foot, their link is compelling: the observed gamma flux [Grechnev V.V. et al., (arXiv:0806.4424), Solar Physics, Vol. 1, October, (2008), 252] reflects into a corresponding one for the neutrinos, almost one to one. Moreover while gamma photons might be absorbed (in deep corona) or at least reduced inside the flaring plasma, the secondaries neutrino are not. So pion neutrinos should be even more abundant than gamma ones. Tens-hundred MeV neutrinos may cross undisturbed the whole Sun, doubling at least their rate respect a unique solar-side for gamma flare. Therefore we obtain minimal bounds opening a windows for neutrino astronomy, already at the edge of present but quite within near future Megaton neutrino detectors. Such detectors are considered mostly to reveal cosmic supernova background or rare Local Group (few Mpc) Supernovas events [Matthew D. Kistler et al. (0810.1959v1)]. However rarest (once a decade), brief (a few minutes) powerful solar neutrino 'flare' may shine and they may overcome by two to three order of magnitude the corresponding steady atmospheric neutrino noise on the Earth, leading in largest Neutrino detector at least to one or to meaning-full few events clustered signals. The voice of such a solar anti-neutrino flare component at a few tens MeVs may induce an inverse beta decay over a vanishing anti-neutrino solar background. Megaton or even inner ten Megaton Ice Cube detector at ten GeV threshold may also reveal traces in hardest energy of solar flares. Icecube

  11. M DWARFS IN SLOAN DIGITAL SKY SURVEY STRIPE 82: PHOTOMETRIC LIGHT CURVES AND FLARE RATE ANALYSIS

    International Nuclear Information System (INIS)

    Kowalski, Adam F.; Hawley, Suzanne L.; Hilton, Eric J.; Becker, Andrew C.; Sesar, Branimir; West, Andrew A.; Bochanski, John J.

    2009-01-01

    We present a flare rate analysis of 50,130 M dwarf light curves in Sloan Digital Sky Survey Stripe 82. We identified 271 flares using a customized variability index to search ∼2.5 million photometric observations for flux increases in the u and g bands. Every image of a flaring observation was examined by eye and with a point-spread function-matching and image subtraction tool to guard against false positives. Flaring is found to be strongly correlated with the appearance of Hα in emission in the quiet spectrum. Of the 99 flare stars that have spectra, we classify eight as relatively inactive. The flaring fraction is found to increase strongly in stars with redder colors during quiescence, which can be attributed to the increasing flare visibility and increasing active fraction for redder stars. The flaring fraction is strongly correlated with |Z| distance such that most stars that flare are within 300 pc of the Galactic plane. We derive flare u-band luminosities and find that the most luminous flares occur on the earlier-type m dwarfs. Our best estimate of the lower limit on the flaring rate (averaged over Stripe 82) for flares with Δu ≥ 0.7 mag on stars with u -1 deg -2 but can vary significantly with the line of sight.

  12. Early lessons from the Turner Valley Gas Plant: 'those smoke stacks got a lot of it'

    Energy Technology Data Exchange (ETDEWEB)

    Finch, D.

    2002-06-01

    Lessons learned (or not learned) since 1924 in Turner Valley in conjunction with the Royalite No. 4, Alberta's famous runaway well, is told. Initially the gas from this well contained 700 grains of hydrogen sulphide per 100 cubic feet of gas, delivered at such high pressure that no compression was necessary until 1938. Various technologies had been tried to scrub the gas, including a soda ash solution trickled down over a trellis of redwood grids in steel towers, absorbing the hydrogen sulphide. As early as 1925, the plant scrubbed 97 per cent of hydrogen sulphide from 45 million cubic feet of gas per day, making it the largest gas scrubbing plant in the world. However, the hydrogen sulphide scrubbed from the gas stream was being pumped out of twin 123-feet tall towers, and discharged into the atmosphere. At least one death is known to have been caused by the hydrogen sulphide, however, it is suspected that many more deaths have occurred on the ranches and homesteads located downwind from the plant, since people there breathed diluted hydrogen sulphide for 27 years. Royalite finally built a sulphur plant and began manufacturing elemental sulphur from the deadly gas processing byproduct. The issue of flaring has been a matter of serious concern in Alberta for a long time. Governments have made a variety of promises, usually prior to elections, to hold the industry to higher environmental standards, but such promises invariably last only a short time. Sooner or later every government appears to succumb to industry demands; after all, a large part of the provincial economy relies on the oil patch, and a significant portion of the provincial budget comes from direct and indirect taxation of the oil industry, the goose that lays the golden egg. To seriously deal with the issue of flaring, Albertans will need substantial changes in the management of the province.

  13. Decrease of the solar flare/solar wind flux ratio in the past several aeons from solar neon and tracks in lunar soil plagioclases

    International Nuclear Information System (INIS)

    Wieler, R.; Etique, Ph.; Signer, P.; Poupeau, G.

    1982-08-01

    The He, Ne, and Ar concentrations and isotopic compositions of mineral separates of six lunar subsurface samples and of two regolith breccias which were exposed to the sun as early as 2 - 3 billion years ago are determined. The results are compared with our noble gas data obtained previously on mineral separates of lunar surface soil samples most of which contain recently implanted solar gases. The mean solar flare track densities were determined on aliquots of several of the plagioclase separates analyzed for noble gases. Solar wind retentive mafic minerals and ilmenites show that a possible secular increase of the 20 Ne/ 22 Ne ratio in the solar wind during the last 2 - 3 Ga. is 20 Ne/ 22 Ne of approximately 11.3 - 11.8, reported for solar flare Ne retained in plagioclase separates from lunar soils. The solar flare track data and the Ne data independently show that plagioclases exposed to the sun over the last 10 8 years recorded a lower mean ratio of solar flare to solar wind intensities than samples exposed about 1 - 3 billion years ago. On the basis of track data these ratios are estimated to differ by a factor approximately 2. (Author) [pt

  14. Statistical relationship between the succeeding solar flares detected by the RHESSI satellite

    Science.gov (United States)

    Balázs, L. G.; Gyenge, N.; Korsós, M. B.; Baranyi, T.; Forgács-Dajka, E.; Ballai, I.

    2014-06-01

    The Reuven Ramaty High Energy Solar Spectroscopic Imager has observed more than 80 000 solar energetic events since its launch on 2002 February 12. Using this large sample of observed flares, we studied the spatiotemporal relationship between succeeding flares. Our results show that the statistical relationship between the temporal and spatial differences of succeeding flares can be described as a power law of the form R(t) ˜ tp with p = 0.327 ± 0.007. We discuss the possible interpretations of this result as a characteristic function of a supposed underlying physics. Different scenarios are considered to explain this relation, including the case where the connectivity between succeeding events is realized through a shock wave in the post Sedov-Taylor phase or where the spatial and temporal relationship between flares is supposed to be provided by an expanding flare area in the sub-diffusive regime. Furthermore, we cannot exclude the possibility that the physical process behind the statistical relationship is the reordering of the magnetic field by the flare or it is due to some unknown processes.

  15. Particle propagation, wave growth and energy dissipation in a flaring flux tube

    Science.gov (United States)

    White, S. M.; Melrose, D. B.; Dulk, G. A.

    1986-01-01

    Wave amplification by downgoing particles in a common flare model is investigated. The flare is assumed to occur at the top of a coronal magnetic flux loop, and results in the heating of plasma in the flaring region. The hot electrons propagate down the legs of the flux tube towards increasing magnetic field. It is simple to demonstrate that the velocity distributions which result in this model are unstable to both beam instabilities and cyclotron maser action. An explanation is presented for the propagation effects on the distribution, and the properties of the resulting amplified waves are explored, concentrating on cyclotron maser action, which has properties (emission in the z mode below the local gyrofrequency) quite different from maser action by other distributions considered in the context of solar flares. The z mode waves will be damped in the coronal plasma surrounding the flaring flux tube and lead to heating there. This process may be important in the overall energy budget of the flare. The downgoing maser is compared with the loss cone maser, which is more likely to produce observable bursts.

  16. MATHEMATICAL MODELLING OF PREFERED SOLUTIONS CHOICE FUNCTION FOR TUBULAR GAS HEATERS BY EXPERIMENTAL INFORMATIONS

    Directory of Open Access Journals (Sweden)

    BARSUK R. V.

    2016-08-01

    Full Text Available Annotation. Problems formulation. The article deals with choice functions building of preferred solutions by experimental information for tubular gas heater working on fuel granules - pellets.Further choice functions using for making technical solutions by tubular gas heaters construction and designing. Recently research analysis. There are works about choice functions construction by separate presents are examined. But full chose functions building by separate presents are not examined. Aims and tasks. There are setting aim to develop full choice functions mathematical model on separate presents by authors. The expert are connect to primary experimental data’s evaluation that estimates separate results by output functions (criteria. Its evaluations issue in experimental points paired comparison’s table form. Thus, there are necessary construct binary choice relations presents on experimental “points” set by expert that then using for full choice function’s constructing. Conclusions. There are choice function’s construction’s sequence are sets. There are posed point comparison results that characterized tubular gas heater’s condition with expert’s evaluation using. Also posed output functions comparisons by which can be characterized improving tubular gas heater’s performance or vice versa.

  17. Development of a biofiltration system to remove hydrogen sulphide from small oil and gas production facilities

    International Nuclear Information System (INIS)

    Dombroski, E.C.; Gaudet, I. D.; Coleman, R. N.

    1997-01-01

    Environmental regulations require sulphur separation in any processing operation that produces more than one tonne of sulphur per day. This leaves about 50 small operations in Alberta where the daily production of sulphur is less than one tonne. In these cases, the extracted acid gases are usually flared. Since flares are often inefficient and do not completely oxidize the hydrogen sulfide, an alternate, cost-effective technology that could replace flaring and eliminate atmospheric discharge would be of considerable interest. Biofiltration is known to be capable of oxidizing hydrogen sulfide in an air stream to non-volatile sulphate. The objective of this paper was to investigate the effectiveness of this technology in controlling H 2 S and SO 2 emissions from sour gas plants. Results of this laboratory-scale experiment were encouraging, justifying further studies on a demonstration-scale to determine if a full-scale biofilter could provide a practical, cost-effective technology for sulfur emission control from gas plants. 9 refs., 7 figs

  18. The Natural History of Flare-Ups in Fibrodysplasia Ossificans Progressiva (FOP): A Comprehensive Global Assessment.

    Science.gov (United States)

    Pignolo, Robert J; Bedford-Gay, Christopher; Liljesthröm, Moira; Durbin-Johnson, Blythe P; Shore, Eileen M; Rocke, David M; Kaplan, Frederick S

    2016-03-01

    Fibrodysplasia ossificans progressiva (FOP) leads to disabling heterotopic ossification (HO) from episodic flare-ups. However, the natural history of FOP flare-ups is poorly understood. A 78-question survey on FOP flare-ups, translated into 15 languages, was sent to 685 classically-affected patients in 45 countries (six continents). Five hundred patients or knowledgeable informants responded (73%; 44% males, 56% females; ages: 1 to 71 years; median: 23 years). The most common presenting symptoms of flare-ups were swelling (93%), pain (86%), or decreased mobility (79%). Seventy-one percent experienced a flare-up within the preceding 12 months (52% spontaneous; 48% trauma-related). Twenty-five percent of those who had received an intramuscular injection reported an immediate flare-up at the injection site, 84% of whom developed HO. Axial flare-ups most frequently involved the back (41.6%), neck (26.4%), or jaw (19.4%). Flare-ups occurred more frequently in the upper limbs before 8 years of age, but more frequently in the lower limbs thereafter. Appendicular flare-ups occurred more frequently at proximal than at distal sites without preferential sidedness. Seventy percent of patients reported functional loss from a flare-up. Thirty-two percent reported complete resolution of at least one flare-up and 12% without any functional loss (mostly in the head or back). The most disabling flare-ups occurred at the shoulders or hips. Surprisingly, 47% reported progression of FOP without obvious flare-ups. Worldwide, 198 treatments were reported; anti-inflammatory agents were most common. Seventy-five percent used short-term glucocorticoids as a treatment for flare-ups at appendicular sites. Fifty-five percent reported that glucocorticoids improved symptoms occasionally whereas 31% reported that they always did. Only 12% reported complete resolution of a flare-up with glucocorticoids. Forty-three percent reported rebound symptoms within 1 to 7 days after completing a course of

  19. Solar flare pion and neutron production

    International Nuclear Information System (INIS)

    Forrest, D.J.; Vestrand, W.T.

    1992-01-01

    During cycle 21, the Gamma Ray Spectrometer on SMM observed three large flares with clear evidence for pion decay gamma rays and high energy neutrons. Two of these had an extended emission phase. The emission observed in these extended phases were clearly different from those observed in the impulsive phase. Compared to the impulsive phase, the extended phase emissions were strongly deficient in electron bremsstrahlung relative to the nuclear line emission in the 1.0-7.0 MeV band and appeared to have a reduced energetic neutron to pion gamma ray emission in the >10 MeV band. These changes can be produced either by a strong hardening of the accelerated ion spectrum together with a relative decrease in the energetic electron spectrum, or by a pronounced change in the geometry of the particle spectrum downwards towards the photosphere. The authors review the observational evidence in terms of these two possibilities. A dramatic change in the energetic particle geometry appears to offer the simplest explanation. If true these two flares represent the first clear evidence of strong particle geometry effects within individual flares

  20. UBV-photometry of flare stars in pleiades

    International Nuclear Information System (INIS)

    Chavushyan, O.S.; Garibdzhanyan, A.T.

    1975-01-01

    The results are presented of UBV-photometry of 283 flare stars at the minimum of brightness in the Pleiad region. A new method has been developed and used of taking into account the background in photographic UBV-photometry with an iris microphotometer. The data obtained indicate that the flare Pleiad stars are located on both sides of the main sequence in the light-luminosity (V,B-V) diagram, while in the (U-B,B-V) diagram they are largely located above the main sequence

  1. A new chemical system solution for acid gas removal

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, M.; Rolker, J.; Witthaut, D.; Schulze, S. [Evonik Industries AG, Hanau (Germany); Buchholz, S. [Evonik Industries AG, Marl (Germany)

    2012-07-01

    An energy-efficient absorbent formulation fors eparating acid gases (e.g. CO{sub 2}, H2S) from gas streams such as natural gas, syngas or flue gas is important for a number of industrial applications. In many cases, a substantial share of their costs is driven by the operational expenditure (OPEX) of the CO{sub 2} separation unit. One possible strategy for reducing OPEX is the improvement of the absorbent performance. Although a number of absorbents for the separation of CO{sub 2} from gas streams exist, there is still a need to develop CO{sub 2} absorbents with an improved absorption performance, less corrosion and foaming, no nitrosamine formation, lower energy requirement and therefore less OPEX. This contribution aims at giving a brief state-of-the-art overview followed by an introduction and performance characterization of a new family of amine-based CO{sub 2} absorbents. High cyclic capacities in the range of 2.9 to 3.2 mol CO{sub 2} kg{sup -1} absorbent and low absorption enthalpies of about -30 kJ mol{sup -1} allow for significant savings in the regeneration energy of the new absorbent system. Calculations with the modified Kremser model indicate a reduction in the specific reboiler heat duty of 45 %. Moreover, the high-performance absorbents developed show much lower corrosion rates than state-of-the-art solutions that are currently employed. (orig.)

  2. Reconnection Fluxes in Eruptive and Confined Flares and Implications for Superflares on the Sun

    Science.gov (United States)

    Tschernitz, Johannes; Veronig, Astrid M.; Thalmann, Julia K.; Hinterreiter, Jürgen; Pötzi, Werner

    2018-01-01

    We study the energy release process of a set of 51 flares (32 confined, 19 eruptive) ranging from GOES class B3 to X17. We use Hα filtergrams from Kanzelhöhe Observatory together with Solar Dynamics Observatory HMI and Solar and Heliospheric Observatory MDI magnetograms to derive magnetic reconnection fluxes and rates. The flare reconnection flux is strongly correlated with the peak of the GOES 1–8 Å soft X-ray flux (c = 0.92, in log–log space) for both confined and eruptive flares. Confined flares of a certain GOES class exhibit smaller ribbon areas but larger magnetic flux densities in the flare ribbons (by a factor of 2). In the largest events, up to ≈50% of the magnetic flux of the active region (AR) causing the flare is involved in the flare magnetic reconnection. These findings allow us to extrapolate toward the largest solar flares possible. A complex solar AR hosting a magnetic flux of 2 × 1023 Mx, which is in line with the largest AR fluxes directly measured, is capable of producing an X80 flare, which corresponds to a bolometric energy of about 7 × 1032 erg. Using a magnetic flux estimate of 6 × 1023 Mx for the largest solar AR observed, we find that flares of GOES class ≈X500 could be produced (E bol ≈ 3 × 1033 erg). These estimates suggest that the present day’s Sun is capable of producing flares and related space weather events that may be more than an order of magnitude stronger than have been observed to date.

  3. Diagnostics of solar flare reconnection

    Directory of Open Access Journals (Sweden)

    M. Karlický

    2004-01-01

    Full Text Available We present new diagnostics of the solar flare reconnection, mainly based on the plasma radio emission. We propose that the high-frequency (600-2000 MHz slowly drifting pulsating structures map the flare magnetic field reconnection. These structures correspond to the radio emission from plasmoids which are formed in the extended current sheet due to tearing and coalescence processes. An increase of the frequency drift of the drifting structures is interpreted as an increase of the reconnection rate. Using this model, time scales of slowly drifting pulsating structure observed during the 12 April 2001 flare by the Trieste radiopolarimeter with high time resolution (1 ms are interpreted as a radio manifestation of electron beams accelerated in the multi-scale reconnection process. For short periods Fourier spectra of the observed structure have a power-law form with power-law indices in the 1.3-1.6 range. For comparison the 2-D MHD numerical modeling of the multi-scale reconnection is made and it is shown that Fourier spectrum of the reconnection dissipation power has also a power-law form, but with power-law index 2. Furthermore, we compute a time evolution of plasma parameters (density, magnetic field etc in the 2-D MHD model of the reconnection. Then assuming a plasma radio emission from locations, where the 'double-resonance' instability generates the upper-hybrid waves due to unstable distribution function of suprathermal electrons, we model radio spectra. Effects of the MHD turbulence are included. The resulting spectra are compared with those observed. It is found, that depending on model parameters the lace bursts and the decimetric spikes can be reproduced. Thus, it is shown that the model can be used for diagnostics of the flare reconnection process. We also point out possible radio signatures of reconnection outflow termination shocks. They are detected as type II-like herringbone structures in the 200-700 MHz frequency range. Finally

  4. Photospheric Spots and Flare on the Active Dwarf Star FR Cnc

    Science.gov (United States)

    Kozhevnikova, A. V.; Kozhevnikov, V. P.; Alekseev, I. Yu.

    2018-03-01

    We perform analysis of new BVRI photometry of young active dwarf star FR Cnc (K7V), obtained at Kourovka astronomical observatory of Ural Federal University with the help of multichannel electrophotometer in February 2010. The lightcurve displays sinusoidal rotation modulation with the amplitude of 0m.15 in V band. Reddening of the brightness at the photometric minimum confirms that this modulation is caused by cold photospheric spots. An analysis of the spottedness distribution in terms of a zonal model based on our own and published data shows that the spots are localized at lower and middle latitudes from 47° to 56°, occupy 10-21% of the star's area, and are colder than the photosphere by 1650 K. A flare was detected on February 3, 2010, at a time corresponding to HJD=2455231. 3136. A maximum amplitude of 0m.11 was observed in the B band, the amplitudes in the V, R, and I bands were 0m.04, 0m.03, and 0m.02, respectively, and the duration of the flare was 32.5 min. It was noted that the flare occurred near the maximum spottedness of the star. The calculated total energy of the flare was 2.4·1033 and 1.3·1033 erg in the B and V bands, respectively. The flare was found to have an afterglow, with an overall increase in the star's brightness by 0m.02 in the B band after the flare compared to the pre-flare level.

  5. The Lived Experience of Lupus Flares: Features, Triggers, and Management in an Australian Female Cohort

    Directory of Open Access Journals (Sweden)

    Marline L. Squance

    2014-01-01

    Full Text Available Individuals living with lupus commonly experience daily backgrounds of symptoms managed to acceptable tolerance levels to prevent organ damage. Despite management, exacerbation periods (flares still occur. Varied clinical presentations and unpredictable symptom exacerbation patterns provide management and assessment challenges. Patient perceptions of symptoms vary with perceived impact, lifestyles, available support, and self-management capacity. Therefore, to increase our understanding of lupus’ health impacts and management, it was important to explore lupus flare characteristics from the patient viewpoint. Lupus flares in 101 Australian female patients were retrospectively explored with the use of a novel flare definition. Qualitative methods were used to explore patient-perceived flare symptoms, triggers, and management strategies adopted to alleviate symptom exacerbations. A mean of 29.9 flare days, with 6.8 discrete flares, was experienced. The study confirmed that patients perceive stress, infection, and UV light as flare triggers and identified new potential triggers of temperature and weather changes, work, and chemical exposure from home cleaning. The majority of flares were self-managed with patients making considered management choices without medical input. Barriers to seeking medical support included appointment timings and past negative experiences reflecting incongruence between clinician and patient views of symptom impact, assessment, and ultimately flare occurrence.

  6. Flares of Nearby, Mid-to-late M-dwarfs Characterized by the MEarth Project

    Science.gov (United States)

    Mondrik, Nicholas; Charbonneau, David; Irwin, Jonathan; Newton, Elisabeth R.

    2017-01-01

    Stellar flares are both a curse and a blessing: Transit and radial velocity searches for exoplanets are hindered by the variability caused by flares, while the characteristics of this variability offer valuable insight into the magnetic properties of the star. We present an analysis of flare events of nearby, mid-to-late M-dwarfs from the MEarth Project. MEarth consists of a northern and a southern array of 8 telescopes each that photometrically monitors most mid-to-late M-dwarfs within 30 parsecs. Although the initial motivation was to search for exoplanet transits, the cadence of approximately 20 minutes is well-suited to capturing long-lived flares. However, MEarth employs a single, wide, red bandpass, which poses challenges to the robust detection of flare events, which are typically bluer in color. Using MEarth data, our team has recently published trigonometric parallaxes and estimates of rotation periods for an unprecedented number of nearby low-mass stars. We also gathered supplementary optical and near infrared spectra of a subset of these stars. We describe here the properties of the flares detected by MEarth, and explore the relation of the presence of flares on individual stars with stellar parameters such as rotational period, mass, and H-alpha equivalent width. We also provide an estimate of flare rate for individual stars by injecting flares into our pipeline.The MEarth project acknowledges funding from the National Science Foundation and the David and Lucile Packard Foundation Fellowship for Science and Engineering. This work was made possible through the support of a grant from the John Templeton Foundation.

  7. Analysis of ultraviolet and X-ray observations of three homologous solar flares from SMM

    Science.gov (United States)

    Cheng, Chung-Chieh; Pallavicini, Roberto

    1987-01-01

    Three homologous flares observed in the UV lines of Fe XXI and O V and in X-rays from the SMM were studied. It was found that: (1) the homology of the flares was most noticeable in Fe XXI and soft X-ray emissions; (2) the three flares shared many of the same loop footprints which were located in O V bright kernals associated with hard X-ray bursts; and (3) in spite of the strong spatial homology, the temporal evolution in UV and X-ray emissions varied from flare to flare. A comparison between the UV observations and photospheric magnetograms revealed that the basic flare configuration was a complex loop system consisting of many loops or bundles of loops.

  8. Sgr A* flares: tidal disruption of asteroids and planets?

    NARCIS (Netherlands)

    Zubovas, K.; Nayakshin, S.; Markoff, S.

    2012-01-01

    It is theoretically expected that a supermassive black hole (SMBH) in the centre of a typical nearby galaxy disrupts a solar-type star every ∼105 yr, resulting in a bright flare lasting for months. Sgr A*, the resident SMBH of the Milky Way, produces (by comparison) tiny flares that last only hours

  9. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Science.gov (United States)

    Nec, Y.; Huculak, G.

    2017-12-01

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy-Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein.

  10. LONG DURATION FLARE EMISSION: IMPULSIVE HEATING OR GRADUAL HEATING?

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman MT 59717-3840 (United States)

    2016-03-20

    Flare emissions in X-ray and EUV wavelengths have previously been modeled as the plasma response to impulsive heating from magnetic reconnection. Some flares exhibit gradually evolving X-ray and EUV light curves, which are believed to result from superposition of an extended sequence of impulsive heating events occurring in different adjacent loops or even unresolved threads within each loop. In this paper, we apply this approach to a long duration two-ribbon flare SOL2011-09-13T22 observed by the Atmosphere Imaging Assembly (AIA). We find that to reconcile with observed signatures of flare emission in multiple EUV wavelengths, each thread should be heated in two phases, an intense impulsive heating followed by a gradual, low-rate heating tail that is attenuated over 20–30 minutes. Each AIA resolved single loop may be composed of several such threads. The two-phase heating scenario is supported by modeling with both a zero-dimensional and a 1D hydrodynamic code. We discuss viable physical mechanisms for the two-phase heating in a post-reconnection thread.

  11. Solar flare leaves sun quaking

    Science.gov (United States)

    1998-05-01

    Dr. Alexander G. Kosovichev, a senior research scientist from Stanford University, and Dr. Valentina V. Zharkova from Glasgow (United Kingdom) University found the tell-tale seismic signature in data on the Sun's surface collected by the Michelson Doppler Imager onboard the Solar and Heliospheric Observatory (SOHO) spacecraft immediately following a moderate-sized flare on July 9, 1996. "Although the flare was a moderate one, it still released an immense amount of energy," said Dr. Craig Deforest, a researcher with the SOHO project. "The energy released is equal to completely covering the Earth's continents with a yard of dynamite and detonating it all at once." SOHO is a joint project of the European Space Agency and NASA. The finding is reported in the May 28 issue of the journal Nature, and is the subject of a press conference at the spring meeting of the American Geophysical Union in Boston, Mass., May 27. The solar quake that the science team recorded looks much like ripples spreading from a rock dropped into a pool of water. But over the course of an hour, the solar waves traveled for a distance equal to 10 Earth diameters before fading into the fiery background of the Sun's photosphere. Unlike water ripples that travel outward at a constant velocity, the solar waves accelerated from an initial speed of 22,000 miles per hour to a maximum of 250,000 miles per hour before disappearing. "People have looked for evidence of seismic waves from flares before, but they didn't have a theory so they didn't know where to look," says Kosovichev. Several years ago Kosovichev and Zharkova developed a theory that can explain how a flare, which explodes in space above the Sun's surface, can generate a major seismic wave in the Sun's interior. According to the currently accepted model of solar flares, the primary explosion creates high-energy electrons (electrically charged subatomic particles). These are funneled down into a magnetic flux tube, an invisible tube of magnetic

  12. Solar flares at submillimeter wavelengths

    Czech Academy of Sciences Publication Activity Database

    Krucker, S.; Gimenez de Castro, C.G.; Hudson, H. S.; Trottet, G.; Bastian, T.S.; Hales, A.S.; Kašparová, Jana; Klein, K. L.; Kretzschmar, M.; Luethi, T.; Mackinnon, A.; Pohjolainen, S.; White, S.M.

    2013-01-01

    Roč. 21, č. 1 (2013), 58/1-58/45 ISSN 0935-4956 Institutional support: RVO:67985815 Keywords : Sun * flares * radio observations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 13.312, year: 2013

  13. A Double Candle-Flame-Shaped Solar Flare Observed by SDO and STEREO

    Science.gov (United States)

    Gou, T.; Liu, R.; Wang, Y.; Liu, K.; Zhuang, B.; Zhang, Q.; Liu, J.

    2015-12-01

    We investigate an M1.4 flare occurring on 2011 January 28 near the northwest solar limb. The flare loop system exhibits a double candle-flame configuration in SDO/AIA's hot passbands, sharing a much larger cusp-shaped structure. The results of DEM analysis show that each candle flame has a similar temperature distribution as the famous Tsuneta flare. STEREO-A provides us a view from directly above the flare, and in SECCHI/EUVI 195 Å the post-flare loops are observed to propagate eastward. We performed a 3D reconstruction of the pos-flare loops with AIA and EUVI data. With the aid of the squashing factor Q based on a potential extrapolation of the photospheric field, we recognized that the footpoints of the post-flare loops were slipping along high-Q lines on the photosphere, and the reconstructed loops share similarity with the filed lines that are traced starting from the high-Q lines. The heights of the loops increase as they slip horizontally eastward, giving the loop-top a velocity of about 10 km/s. An extremely large EUV late phase in Fe XVI 33.5 nm observed by SDO/EVE is suggested to be related to the slipping magnetic reconnection occurring in the quasi-separatrix layers (QSLs) whose photosheric footprints are featured by the high-Q lines.

  14. Study of the behaviour of the equatorial ionization anomaly (EIA) during solar flares

    Science.gov (United States)

    Aggarwal, Malini; Astafyeva, Elvira

    2014-05-01

    A solar flare occurring in the sun's chromosphere is observed in various wavebands (radio to x-rays). The response of the solar flare which causes sudden changes in the earth's ionosphere is not yet well understood though investigations suggested that its impact depends on the size and location of occurrence of solar flare on sun. Considering this, we have carried an investigation to study the response of two strong and gradual solar flares: 2 Apr 2001 (X20, limb) and 7 Feb 2010 (M6.4, disk) on the earth's equatorial-low latitude regions using multi-technique observations of satellite and ground-based instruments. We found a weakening of strength of equatorial ionization anomaly (EIA) in total electron content during both the flares as observed by TOPEX, JASON-1 and JASON-2 altimeter measurements. The H component of the geomagnetic field also shows a sudden change at equatorial and low latitude stations in the sunlit hemisphere during the flare. The observations of ionosonde at low-latitudes indicate a strong absorption of higher-frequency radio signals. The detail response of these flare on EIA of the earth's ionosphere will be presented and discussed.

  15. Intracanal medications and antibiotics in the control of interappointment flare-ups.

    Science.gov (United States)

    Rimmer, A

    1991-12-01

    Acute exacerbation of symptoms, or "flare-up," after the debridement of the root canals and provisional restoration is a well-known postoperative complication of endodontic treatment. In this clinical study, various types of intracanal medications were compared for their ability to decrease interappointment flare-ups. The result showed that use of intracanal medicaments containing anti-inflammatory agents in combination with the administration of prophylactic systematic antibiotics was the most effective method of controlling interappointment flare-ups.

  16. Twin Screw Extruder Production of MTTP Decoy Flares SERDP WP-1240

    National Research Council Canada - National Science Library

    Campbell, Carol

    2005-01-01

    The objective of this effort is to develop an environmentally acceptable decoy flare formulation and process to produce aircraft decoy flares without the use of HAP or Volatile Organic Compounds (VOC...

  17. Strategic behavior and international benchmarking for monopoly price regulation. The case of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Dagobert L. [Rice Univ., Houston, TX (US). Dept. of Economics and Baker Inst. (MS-22); Rosellon, Juan [Centro de Investigacion y Docencia Economicas (CIDE), Mexico, D.F. (Mexico); Deutsches Inst. fuer Wirtschaftsforschung, Berlin (Germany)

    2010-07-01

    This paper looks into various models that address strategic behavior in the supply of gas by the Mexican monopoly Pemex. The paper has three very strong technical results. First, the netback pricing rule for the price of domestic natural gas (based on a Houston benchmark price) leads to discontinuities in Pemex's revenue function. Second, having Pemex pay for the gas it uses and the gas it flares increases the value of the Lagrange multiplier associated with the gas processing constraint. Third, if the gas processing constraint is binding, having Pemex pay for the gas it uses and flares does not change the short run optimal solution for the optimization problem, so it will have no impact on short-run behavior. These results imply three clear policy recommendations. The first is that the arbitrage point be fixed by the amount of gas Pemex has the potential to supply in the absence of processing and gathering constraints. The second is that Pemex be charged for the gas it uses in production and the gas it flares. The third is that investment in gas processing and pipeline should be in a separate account from other Pemex investment. (orig.)

  18. Using natural language processing and machine learning to identify gout flares from electronic clinical notes.

    Science.gov (United States)

    Zheng, Chengyi; Rashid, Nazia; Wu, Yi-Lin; Koblick, River; Lin, Antony T; Levy, Gerald D; Cheetham, T Craig

    2014-11-01

    Gout flares are not well documented by diagnosis codes, making it difficult to conduct accurate database studies. We implemented a computer-based method to automatically identify gout flares using natural language processing (NLP) and machine learning (ML) from electronic clinical notes. Of 16,519 patients, 1,264 and 1,192 clinical notes from 2 separate sets of 100 patients were selected as the training and evaluation data sets, respectively, which were reviewed by rheumatologists. We created separate NLP searches to capture different aspects of gout flares. For each note, the NLP search outputs became the ML system inputs, which provided the final classification decisions. The note-level classifications were grouped into patient-level gout flares. Our NLP+ML results were validated using a gold standard data set and compared with the claims-based method used by prior literatures. For 16,519 patients with a diagnosis of gout and a prescription for a urate-lowering therapy, we identified 18,869 clinical notes as gout flare positive (sensitivity 82.1%, specificity 91.5%): 1,402 patients with ≥3 flares (sensitivity 93.5%, specificity 84.6%), 5,954 with 1 or 2 flares, and 9,163 with no flare (sensitivity 98.5%, specificity 96.4%). Our method identified more flare cases (18,869 versus 7,861) and patients with ≥3 flares (1,402 versus 516) when compared to the claims-based method. We developed a computer-based method (NLP and ML) to identify gout flares from the clinical notes. Our method was validated as an accurate tool for identifying gout flares with higher sensitivity and specificity compared to previous studies. Copyright © 2014 by the American College of Rheumatology.

  19. High-resolution Observations of Flares in an Arch Filament System

    Science.gov (United States)

    Su, Yingna; Liu, Rui; Li, Shangwei; Cao, Wenda; Ahn, Kwangsu; Ji, Haisheng

    2018-03-01

    We study five sequential solar flares (SOL2015-08-07) occurring in Active Region 12396 observed with the Goode Solar Telescope (GST) at the Big Bear Solar Observatory, complemented by Interface Region Imaging Spectrograph and SDO observations. The main flaring region is an arch filament system (AFS) consisting of multiple bundles of dark filament threads enclosed by semicircular flare ribbons. We study the magnetic configuration and evolution of the active region by constructing coronal magnetic field models based on SDO/HMI magnetograms using two independent methods, i.e., the nonlinear force-free field (NLFFF) extrapolation and the flux rope insertion method. The models consist of multiple flux ropes with mixed signs of helicity, i.e., positive (negative) in the northern (southern) region, which is consistent with the GST observations of multiple filament bundles. The footprints of quasi-separatrix layers (QSLs) derived from the extrapolated NLFFF compare favorably with the observed flare ribbons. An interesting double-ribbon fine structure located at the east border of the AFS is consistent with the fine structure of the QSL’s footprint. Moreover, magnetic field lines traced along the semicircular footprint of a dome-like QSL surrounding the AFS are connected to the regions of significant helicity and Poynting flux injection. The maps of magnetic twist show that positive twist became dominant as time progressed, which is consistent with the injection of positive helicity before the flares. We hence conclude that these circular shaped flares are caused by 3D magnetic reconnection at the QSLs associated with the AFS possessing mixed signs of helicity.

  20. A RECONNECTION-DRIVEN MODEL OF THE HARD X-RAY LOOP-TOP SOURCE FROM FLARE 2004 FEBRUARY 26

    Energy Technology Data Exchange (ETDEWEB)

    Longcope, Dana; Qiu, Jiong; Brewer, Jasmine [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

    2016-12-20

    A compact X-class flare on 2004 February 26 showed a concentrated source of hard X-rays at the tops of the flare’s loops. This was analyzed in previous work and interpreted as plasma heated and compressed by slow magnetosonic shocks (SMSs) generated during post-reconnection retraction of the flux. That work used analytic expressions from a thin flux tube (TFT) model, which neglected many potentially important factors such as thermal conduction and chromospheric evaporation. Here we use a numerical solution of the TFT equations to produce a more comprehensive and accurate model of the same flare, including those effects previously omitted. These simulations corroborate the prior hypothesis that slow-mode shocks persist well after the retraction has ended, thus producing a compact, loop-top source instead of an elongated jet, as steady reconnection models predict. Thermal conduction leads to densities higher than analytic estimates had predicted, and evaporation enhances the density still higher, but at lower temperatures. X-ray light curves and spectra are synthesized by convolving the results from a single TFT simulation with the rate at which flux is reconnected, as measured through motion of flare ribbons, for example. These agree well with light curves observed by RHESSI and GOES and spectra from RHESSI . An image created from a superposition of TFT model runs resembles one produced from RHESSI observations. This suggests that the HXR loop-top source, at least the one observed in this flare, could be the result of SMSs produced in fast reconnection models like Petschek’s.

  1. Stellar CME candidates: towards a stellar CME-flare relation

    Science.gov (United States)

    Paraskevi Moschou, Sofia; Drake, Jeremy J.; Cohen, Ofer; Alvarado-Gomez, Julian D.; Garraffo, Cecilia

    2018-06-01

    For decades the Sun has been the only star that allowed for direct CME observations. Recently, with the discovery of multiple extrasolar systems, it has become imperative that the role of stellar CMEs be assessed in the context of exoplanetary habitability. Solar CMEs and flares show a higher association with increasing flaring energy, with strong flares corresponding to large and fast CMEs. As argued in earlier studies, extrasolar environments around active stars are potentially dominated by CMEs, as a result of their extreme flaring activity. This has strong implications for the energy budget of the system and the atmospheric erosion of orbiting planets.Nevertheless, with current instrumentation we are unable to directly observe CMEs in even the closest stars, and thus we have to look for indirect techniques and observational evidence and signatures for the eruption of stellar CMEs. There are three major observational techniques for tracing CME signatures in other stellar systems, namely measuring Type II radio bursts, Doppler shifts in UV/optical lines or transient absorption in the X-ray spectrum. We present observations of the most probable stellar CME candidates captured so far and examine the different observational techniques used together with their levels of uncertainty. Assuming that they were CMEs, we try to asses their kinematic and energetic characteristics and place them in an extension of the well-established solar CME-flare energy scaling law. We finish by discussing future observations for direct measurements.

  2. IMPLOSION OF CORONAL LOOPS DURING THE IMPULSIVE PHASE OF A SOLAR FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Simões, P. J. A.; Fletcher, L.; Hudson, H. S.; Russell, A. J. B., E-mail: paulo.simoes@glasgow.ac.uk, E-mail: lyndsay.fletcher@glasgow.ac.uk, E-mail: arussell@maths.dundee.ac.uk, E-mail: hhudson@ssl.berkeley.edu [SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2013-11-10

    We study the relationship between implosive motions in a solar flare, and the energy redistribution in the form of oscillatory structures and particle acceleration. The flare SOL2012-03-09T03:53 (M6.4) shows clear evidence for an irreversible (stepwise) coronal implosion. Extreme-ultraviolet (EUV) images show at least four groups of coronal loops at different heights overlying the flaring core undergoing fast contraction during the impulsive phase of the flare. These contractions start around a minute after the flare onset, and the rate of contraction is closely associated with the intensity of the hard X-ray and microwave emissions. They also seem to have a close relationship with the dimming associated with the formation of the coronal mass ejection and a global EUV wave. Several studies now have detected contracting motions in the corona during solar flares that can be interpreted as the implosion necessary to release energy. Our results confirm this, and tighten the association with the flare impulsive phase. We add to the phenomenology by noting the presence of oscillatory variations revealed by Geostationary Operational Environmental Satellite soft X-rays (SXR) and spatially integrated EUV emission at 94 and 335 Å. We identify pulsations of ≈60 s in SXR and EUV data, which we interpret as persistent, semi-regular compressions of the flaring core region which modulate the plasma temperature and emission measure. The loop oscillations, observed over a large region, also allow us to provide rough estimates of the energy temporarily stored in the eigenmodes of the active-region structure as it approaches its new equilibrium.

  3. PROBING THE FLARE ATMOSPHERES OF M DWARFS USING INFRARED EMISSION LINES

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Sarah J.; Kowalski, Adam F.; Hawley, Suzanne L.; Hilton, Eric J.; Wisniewski, John P.; Tofflemire, Benjamin M., E-mail: sjschmidt@astro.washington.edu [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada (Canada)

    2012-01-20

    We present the results of a campaign to monitor active M dwarfs using infrared spectroscopy, supplemented with optical photometry and spectroscopy. We detected 16 flares during nearly 50 hr of observations on EV Lac, AD Leo, YZ CMi, and VB 8. The three most energetic flares also showed infrared emission, including the first reported detections of P{beta}, P{gamma}, He I {lambda}10830, and Br{gamma} during an M dwarf flare. The strongest flare ({Delta}u = 4.02 on EV Lac) showed emission from H{gamma}, H{delta}, He I {lambda}4471, and Ca II K in the UV/blue and P{beta}, P{gamma}, P{delta}, Br{gamma}, and He I {lambda}10830 in the infrared. The weaker flares ({Delta}u = 1.68 on EV Lac and {Delta}U = 1.38 on YZ CMi) were only observed with photometry and infrared spectroscopy; both showed emission from P{beta}, P{gamma}, and He I {lambda}10830. The strongest infrared emission line, P{beta}, occurred in the active mid-M dwarfs with a duty cycle of {approx}3%-4%. To examine the most energetic flare, we used the static NLTE radiative transfer code RH to produce model spectra based on a suite of one-dimensional model atmospheres. Using a hotter chromosphere than previous one-dimensional atmospheric models, we obtain line ratios that match most of the observed emission lines.

  4. FLARE-GENERATED TYPE II BURST WITHOUT ASSOCIATED CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Magdalenic, J.; Marque, C.; Zhukov, A. N. [Solar-Terrestrial Center of Excellence, SIDC, Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Brussels (Belgium); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, HR-10000 Zagreb (Croatia); Veronig, A., E-mail: Jasmina.Magdalenic@oma.be [IGAM/Kanzelhoehe Observatory, Institut of Physics, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

    2012-02-20

    We present a study of the solar coronal shock wave on 2005 November 14 associated with the GOES M3.9 flare that occurred close to the east limb (S06 Degree-Sign E60 Degree-Sign ). The shock signature, a type II radio burst, had an unusually high starting frequency of about 800 MHz, indicating that the shock was formed at a rather low height. The position of the radio source, the direction of the shock wave propagation, and the coronal electron density were estimated using Nancay Radioheliograph observations and the dynamic spectrum of the Green Bank Solar Radio Burst Spectrometer. The soft X-ray, H{alpha}, and Reuven Ramaty High Energy Solar Spectroscopic Imager observations show that the flare was compact, very impulsive, and of a rather high density and temperature, indicating a strong and impulsive increase of pressure in a small flare loop. The close association of the shock wave initiation with the impulsive energy release suggests that the impulsive increase of the pressure in the flare was the source of the shock wave. This is supported by the fact that, contrary to the majority of events studied previously, no coronal mass ejection was detected in association with the shock wave, although the corresponding flare occurred close to the limb.

  5. Parameterizations of Chromospheric Condensations in dG and dMe Model Flare Atmospheres

    Science.gov (United States)

    Kowalski, Adam F.; Allred, Joel C.

    2018-01-01

    The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic (RHD) simulations in 1D have shown that high energy deposition rates from electron beams produce two flaring layers at T ∼ 104 K that develop in the chromosphere: a cooling condensation (downflowing compression) and heated non-moving (stationary) flare layers just below the condensation. These atmospheres reproduce several observed phenomena in flare spectra, such as the red-wing asymmetry of the emission lines in solar flares and a small Balmer jump ratio in M dwarf flares. The high beam flux simulations are computationally expensive in 1D, and the (human) timescales for completing NLTE models with adaptive grids in 3D will likely be unwieldy for some time to come. We have developed a prescription for predicting the approximate evolved states, continuum optical depth, and emergent continuum flux spectra of RHD model flare atmospheres. These approximate prescriptions are based on an important atmospheric parameter: the column mass ({m}{ref}) at which hydrogen becomes nearly completely ionized at the depths that are approximately in steady state with the electron beam heating. Using this new modeling approach, we find that high energy flux density (>F11) electron beams are needed to reproduce the brightest observed continuum intensity in IRIS data of the 2014 March 29 X1 solar flare, and that variation in {m}{ref} from 0.001 to 0.02 g cm‑2 reproduces most of the observed range of the optical continuum flux ratios at the peak of M dwarf flares.

  6. Magnetohydrodynamic and thermal processes in solar flare energy build-up and release

    International Nuclear Information System (INIS)

    Tend, W. van.

    1979-01-01

    A solar flare can be described as an instability in the upper solar atmosphere that converts 10 28 ergs to 10 32 ergs of magnetic energy into other forms of energy, mainly kinetic energy. The solar flare gives rise to a wealth of observable phenomena. The author develops a fairly simple model to explain many of these apparently very diverse features of solar flares. (Auth.)

  7. VizieR Online Data Catalog: Bayesian method for detecting stellar flares (Pitkin+, 2014)

    Science.gov (United States)

    Pitkin, M.; Williams, D.; Fletcher, L.; Grant, S. D. T.

    2015-05-01

    We present a Bayesian-odds-ratio-based algorithm for detecting stellar flares in light-curve data. We assume flares are described by a model in which there is a rapid rise with a half-Gaussian profile, followed by an exponential decay. Our signal model also contains a polynomial background model required to fit underlying light-curve variations in the data, which could otherwise partially mimic a flare. We characterize the false alarm probability and efficiency of this method under the assumption that any unmodelled noise in the data is Gaussian, and compare it with a simpler thresholding method based on that used in Walkowicz et al. We find our method has a significant increase in detection efficiency for low signal-to-noise ratio (S/N) flares. For a conservative false alarm probability our method can detect 95 per cent of flares with S/N less than 20, as compared to S/N of 25 for the simpler method. We also test how well the assumption of Gaussian noise holds by applying the method to a selection of 'quiet' Kepler stars. As an example we have applied our method to a selection of stars in Kepler Quarter 1 data. The method finds 687 flaring stars with a total of 1873 flares after vetos have been applied. For these flares we have made preliminary characterizations of their durations and and S/N. (1 data file).

  8. Effect of Particle Acceleration Process on the Flare Characteristics of ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    J. Astrophys. Astr. (2002) 23, 95–99. Effect of Particle Acceleration Process on the Flare Characteristics of. Blazars. S. Bhattacharyya, S. Sahayanathan & C. L. Kaul Nuclear Research Laboratory,. Bhabha Atomic Research Centre, Mumbai 400 085, India. Abstract. Following the kinetic equation approach, we study the flare.

  9. The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Adam F. [Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Ave, Boulder, CO 80305 (United States); Allred, Joel C.; Daw, Adrian [NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Cauzzi, Gianna [INAF-Osservatorio Astrofisico di Arcetri, I-50125 Firenze (Italy); Carlsson, Mats, E-mail: Adam.Kowalski@lasp.colorado.edu [Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, NO-0315 Oslo (Norway)

    2017-02-10

    The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager . We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe ii chromospheric emission line profiles observed in the impulsive phase.

  10. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Energy Technology Data Exchange (ETDEWEB)

    Nec, Y [Thompson Rivers University, Kamloops, British Columbia (Canada); Huculak, G, E-mail: cranberryana@gmail.com, E-mail: greg@gnhconsulting.ca [GNH Consulting, Delta, British Columbia (Canada)

    2017-12-15

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy–Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein. (paper)

  11. Solution of weakly compressible isothermal flow in landfill gas collection networks

    International Nuclear Information System (INIS)

    Nec, Y; Huculak, G

    2017-01-01

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy–Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein. (paper)

  12. Proton Flares in Solar Activity Complexes: Possible Origins and Consequences

    Science.gov (United States)

    Isaeva, E. S.; Tomozov, V. M.; Yazev, S. A.

    2018-03-01

    Solar flares observed during the 24th solar-activity cycle and accompanied by fluxes of particles detected at the Earth's orbit with intensities exceeding 10 particles cm-2 s-1 and energies of more than 10 MeV per particle mainly occurred in activity complexes (82% of cases), with 80% of these occurring no more than 20 heliographic degrees from the nearest coronal holes. The correlation between the X-ray classes of flares and the proton fluxes detected at the Earth's orbit is weak. The work presented here supports the hypothesis that the leakage of particles into the heliosphere is due to the existence of long-lived magnetic channels, which facilitate the transport of flare-accelerated particles into the boundary regions of open magnetic structures of coronal holes. The possible contribution of exchange reconnection in the formation of such channels and the role of exchange reconnection in the generation of flares are discussed.

  13. VERY LONG-PERIOD PULSATIONS BEFORE THE ONSET OF SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Baolin; Huang, Jing; Tan, Chengming; Zhang, Yin [Key Laboratory of Solar Activity, National Astronomical Observatories of Chinese Academy of Sciences, Beijing 100012 (China); Yu, Zhiqiang, E-mail: bltan@nao.cas.cn [School of Astronomy and Space Sciences, University of Chinese Academy of Sciences, Beijing 100049 (China)

    2016-12-20

    Solar flares are the most powerful explosions occurring in the solar system, which may lead to disastrous space weather events and impact various aspects of our Earth. It remains a big challenge in modern astrophysics to understand the origin of solar flares and predict their onset. Based on the analysis of soft X-ray emission observed by the Geostationary Operational Environmental Satellite , this work reports a new discovery of very long-periodic pulsations occurring in the preflare phase before the onset of solar flares (preflare-VLPs). These pulsations typically have periods of 8–30 min and last for about 1–2 hr. They are possibly generated from LRC oscillations of plasma loops where electric current dominates the physical process during magnetic energy accumulation in the source region. Preflare-VLPs provide essential information for understanding the triggering mechanism and origin of solar flares, and may be a convenient precursory indicator to help us respond to solar explosions and the corresponding disastrous space weather events.

  14. Flare Ribbon Expansion and Energy Release Ayumi Asai , Takaaki ...

    Indian Academy of Sciences (India)

    2001-04-10

    1Nobeyama Solar Radio Observatory, Minamisaku, Nagano, 384-1305, Japan. ... X2.3 solar flare which occurred on April 10, 2001. .... In the right panel of. Fig. 3, we show the temporal variation of the physical parameters, such as Bp, vf , ˙ , and S along a slit line. Here, we defined vf as the speed of the flare-ribbon ...

  15. Are All Flare Ribbons Simply Connected to the Corona?

    Energy Technology Data Exchange (ETDEWEB)

    Judge, Philip G. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Paraschiv, Alin; Lacatus, Daniela; Donea, Alina [Monash Center for Astrophysics, School of Mathematical Science, Monash University, Victoria 3800 (Australia); Lindsey, Charlie, E-mail: judge@ucar.edu, E-mail: alina.donea@monash.edu, E-mail: alin.paraschiv@monash.edu, E-mail: daniela.lacatus@monash.edu, E-mail: indsey@cora.nwra.com [Northwest Research Associates, 3380 Mitchell Lane, Boulder, CO 80301 (United States)

    2017-04-01

    We consider the observational basis for the belief that flare ribbons in the chromosphere result from energy transport from the overlying corona. We study ribbons of small flares using magnetic and intensity data from the Hinode , Solar Dynamics Observatory , and IRIS missions. While most ribbons appear connected to the corona and overlie regions of significant vertical magnetic field, we examine one ribbon with no clear evidence for such connections. Evolving horizontal magnetic fields seen with Hinode suggest that reconnection with preexisting fields below the corona can explain the data. The identification of just one, albeit small, ribbon, with no apparent connection to the corona, leads us to conclude that at least two mechanisms are responsible for the heating that leads to flare ribbon emission.

  16. DOES A SCALING LAW EXIST BETWEEN SOLAR ENERGETIC PARTICLE EVENTS AND SOLAR FLARES?

    International Nuclear Information System (INIS)

    Kahler, S. W.

    2013-01-01

    Among many other natural processes, the size distributions of solar X-ray flares and solar energetic particle (SEP) events are scale-invariant power laws. The measured distributions of SEP events prove to be distinctly flatter, i.e., have smaller power-law slopes, than those of the flares. This has led to speculation that the two distributions are related through a scaling law, first suggested by Hudson, which implies a direct nonlinear physical connection between the processes producing the flares and those producing the SEP events. We present four arguments against this interpretation. First, a true scaling must relate SEP events to all flare X-ray events, and not to a small subset of the X-ray event population. We also show that the assumed scaling law is not mathematically valid and that although the flare X-ray and SEP event data are correlated, they are highly scattered and not necessarily related through an assumed scaling of the two phenomena. An interpretation of SEP events within the context of a recent model of fractal-diffusive self-organized criticality by Aschwanden provides a physical basis for why the SEP distributions should be flatter than those of solar flares. These arguments provide evidence against a close physical connection of flares with SEP production.

  17. Flare stars and Pascal distribution

    International Nuclear Information System (INIS)

    Muradian, R.

    1994-07-01

    Observed statistics of stellar flares are described by Pascal or Negative Binomial Distribution. The analogy with other classes of chaotic production mechanisms such as hadronic particle multiplicity distributions and photoelectron counts from thermal sources is noticed. (author). 12 refs

  18. Statistical properties of solar flares and coronal mass ejections through the solar cycle

    International Nuclear Information System (INIS)

    Telloni, Daniele; Antonucci, Ester; Carbone, Vincenzo; Lepreti, Fabio

    2016-01-01

    Waiting Time Distributions (WTDs) of solar flares are investigated all through the solar cycle. The same approach applied to Coronal Mass Ejections (CMEs) in a previous work is considered here for flare occurrence. Our analysis reveals that flares and CMEs share some common statistical properties, which result dependent on the level of solar activity. Both flares and CMEs seem to independently occur during minimum solar activity phases, whilst their WTDs significantly deviate from a Poisson function at solar maximum, thus suggesting that these events are correlated. The characteristics of WTDs are constrained by the physical processes generating those eruptions associated with flares and CMEs. A scenario may be drawn in which different mechanisms are actively at work during different phases of the solar cycle. Stochastic processes, most likely related to random magnetic reconnections of the fi