1,447 research outputs found

    Statistics of "Cold" Early Impulsive Solar Flares in X-ray and Microwave domains

    Full text link
    Solar flares often happen after a preflare / preheating phase, which is almost or entirely thermal. In contrast, there are the so-called early impulsive flares that do not show a (significant) preflare heating but instead often show the Neupert effect--a relationship where the impulsive phase is followed by a gradual, cumulative-like, thermal response. This has been interpreted as a dominance of nonthermal energy release at the impulsive phase, even though a similar phenomenology is expected if the thermal and nonthermal energies are released in comparable amounts at the impulsive phase. Nevertheless, some flares do show a good quantitative correspondence between the nonthermal electron energy input and plasma heating, in such cases the thermal response was weak, which results in calling them "cold" flares. We undertook a systematic search of such events among early impulsive flares registered by Konus-Wind instrument in the triggered mode from 11/1994 to 04/2017 and selected 27 cold flares based on relationships between HXR (Konus-Wind) and SXR (GOES) emission. For these events we put together all available microwave data from different instruments. We obtained temporal and spectral parameters of HXR and microwave emissions of the events and examined correlations between them. We found that, compared with a `mean' flare, the cold flares: (i) are weaker, shorter, and harder in the X-ray domain, (ii) are harder and shorter, but not weaker in the microwaves, (iii) have a significantly higher spectral peak frequencies in the microwaves. We discuss the possible physical reasons for these distinctions and implication of the finding.Comment: Accepted for publication in Ap

    A study of phase separation processes in presence of dislocations in binary systems subjected to irradiation

    Full text link
    Dislocation-assisted phase separation processes in binary systems subjected to irradiation effect are studied analytically and numerically. Irradiation is described by athermal atomic mixing in the form of ballistic flux with spatially correlated stochastic contribution. While studying the dynamics of domain size growth we have shown that the dislocation mechanism of phase decomposition delays the ordering processes. It is found that spatial correlations of the ballistic flux noise cause segregation of dislocation cores in the vicinity of interfaces effectively decreasing the interface width. A competition between regular and stochastic components of the ballistic flux is discussed.Comment: 22 pages, 11 figure

    A Cold Flare With Delayed Heating

    Full text link
    Recently, a number of peculiar flares have been reported, which demonstrate significant non-thermal particle signatures with a low, if any, thermal emission, that implies close association of the observed emission with the primary energy release/electron acceleration region. This paper presents a flare that appears a "cold" one at the impulsive phase, while displaying a delayed heating later on. Using HXR data from \kw, microwave observations by SSRT, RSTN, NoRH and NoRP, context observations, and 3D 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 interaction between a small and a big loop and the accelerated particles divided in roughly equal numbers between them. Precipitation of the electrons from the small loop produced only 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 the coronal plasma heating but no or only weak chromospheric evaporation, and thus unusually weak soft X-ray emission. Energy losses of fast electrons in the big tenuous loop were slow resulting 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 electric force along the magnetic field of the small loop. The accelerated particle transport in big loop was primarily mediated by turbulent waves like in the other reported cold flares.Comment: ApJ accepted, 18 pp., 13 figure

    CUSTOMER ORIENTED IDEATION AND ITS IMPACT ON CUSTOMER ADOPTION OF NEW SOLUTIONS

    Get PDF
    Customer adoption of new solutions is critical for the development of the modern business environment, and both academics and practitioners have been investigating this notion to uncover the customer adoption patterns to progress business and withstand competition. Despite the variety of marketing research techniques and practices commonly used to obtain customer data it has been said that the customers that “talk the talk” do not always “walk the walk” of innovation adoption. The challenge remains unchanged: making innovation accessible and easy to adopt in consumers’ everyday lives. This thesis is looking into the processes of creating new solutions to identify the key drivers within the ideation processes that facilitate adoption. The research inquiry is supported by the tendencies in the industry, where, despite the increasing number of new technologies and approaches aimed to develop better products, the success-to-failure ratios remain quite low. The aim of the study is to design an integrative theoretical framework, explaining the drivers of ideation, the impact of customer orientation within ideation, and the influence it has on innovation adoption. The author used integrated methodology, combining the best practices of the deductive approach, commonly applied in conceptual works, and qualitative research methodology, where further insights were uncovered via interviews and a focus group. In this research project, the integrated methodology has been applied to combine the strengths of each of the research techniques and uncover insights into the complex notions and relationships under investigation. The findings include the introduction of COI and the three-dimensional model, facilitating the solutions development practice, aiming to help achieve a more sustainable growth within the service industries. The author has introduced a novel notion of Customer Oriented Ideation (COI) that focuses on the use of customer insights within the solutions development process and its impact on the market success. The author has also developed a questionnaire for further quantitative investigation of the framework, and further refined it via a pilot study

    Wind regime peculiarities in the lower thermosphere in the winter of 1983/84

    Get PDF
    Temporal variations of prevailing winds at 90 to 100 km obtained from measurements carried out in winter 1983 to 1984 at three sites in the USSR and two sites in East Germany are reported. These variations are compared with those of the thermal stratospheric regime. Measurements were carried out using the drifts D2 method (meteor wind radar) and the D1 method (ionospheric drifts). Temporal variations of zonal and meridional prevailing wind components for all the sites are given. Also presented are zonal wind data obtained using the partial reflection wind radar. Wind velocity values were obtained by averaging data recorded at between 105 and 91 km altitude. Wind velocity data averaged in such a way can be related to about the same height interval to which the data obtained by the meteor radar and ionospheric methods at other sites, i.e., the mean height of the meteor zone (about 95 km). The results presented show that there are significant fluctuations about the seasonal course of both zonal and meridional prevailing winds

    Securing tropical forest carbon: the contribution of protected areas to REDD

    Get PDF
    Forest loss and degradation in the tropics contribute 6-17% of all greenhouse gas emissions. Protected areas cover 217.2 million ha (19.6%) of the world's humid tropical forests and contain c. 70.3 petagrams of carbon (Pg C) in biomass and soil to 1 m depth. Between 2000 and 2005, we estimate that 1.75 million ha of forest were lost from protected areas in humid tropical forests, causing the emission of 0.25-0.33 Pg C. Protected areas lost about half as much carbon as the same area of unprotected forest. We estimate that the reduction of these carbon emissions from ongoing deforestation in protected sites in humid tropical forests could be valued at USD 6,200-7,400 million depending on the land use after clearance. This is >1.5 times the estimated spending on protected area management in these regions. Improving management of protected areas to retain forest cover better may be an important, although certainly not sufficient, component of an overall strategy for reducing emissions from deforestation and forest degradation (REDD
    corecore