363 research outputs found

    More frequencies of KUV 02464+3239

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    Preliminary results on KUV 02464+3239, a pulsating DA white dwarf are presented. Located near the red edge of the DAV instability strip, KUV 02464+3239 shows large amplitude and long period pulsation modes. Up to now only one mode was known from a 50-minute-long light curve. Our more extended observations allowed the identification of three additional frequencies. The presence of previously known harmonics were confirmed and weak subharmonics are also noticeable at some parts of the light curve. This suggests the dominance of nonlinear pulsation effects from time to time.Comment: 3 pages, 3 eps figures; has been accepted for publication in Astronomische Nachrichten (Vol. 8, 2007), proceedings of the British-Hungarian-French N+N+N Workshop for Young Researcher

    Generation of a Combined Dataset of Simulated Radar and EO/IR Imagery

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    In the world of remote sensing, both radar and EO/IR (electro-optical/infrared) sensors carry with them unique information useful to the imaging community. Radar has the capability of imaging through all types of weather, day or night. EO/IR produces radiance maps and frequently images at much finer resolution than radar. While each of these systems is valuable to imaging, there exists unknown territory in the imaging community as to the value added in combining the best of both these worlds. This work will begin to explore the challenges in simulating a scene in both a radar tool called Xpatch and an EO/IR tool called DIRSIG (Digital Imaging and Remote Sensing Image Generation). The capabilities and limitations inherent to both radar and EO/IR are similar in the image simulation tools, so the work done in a simulated environment will carry over to the real-world environment as well. The goal of this effort is to demonstrate an environment where EO/IR and radar images of common scenes can be simulated. Once demonstrated, this environment would be used to facilitate trade studies of various multi-sensor instrument design and exploitation algorithm concepts. The synthetic data generated will be compared to existing measured data to demonstrate the validity of the experiment

    A Classification of Single-Phase Transformerless Inverter Topologies for Photovoltaic Applications

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    © 2018 IEEE. In Photovoltaic (PV) applications, a transformer is often used to provide galvanic isolation and voltage ratio transformations. However, a transformer based inverter is bulky and has high conduction losses, therefore lead to a reduction in the inverter efficiency. To overcome this issue, the transformerless inverter topologies are addressed widely, but the main challenge of a transformerless inverter is common mode issue. Numerous topological modifications with their control and modulation techniques makes them difficult to follow, generalize and highlight the advantages and disadvantages. To address the issue, this paper gives an overview on transformerless inverter and classify them into subsection to discuss the merit and demerit of some of the major topologies. Five subsections based on common mode behavior, voltage clamping and decoupling techniques have been demonstrated (i.e., common ground, mid-point clamping, AC-decoupling, DC-decoupling and AC+DC decoupling). To verify the finding and for general consensus, major transformerless topologies are simulated using PLECS. A general summary is presented at the end to stimulate readers to acknowledge the problems and identify solutions

    Phenotyping under extreme weather conditions and microsatellite based genotyping of some Hungarian grape cultivars

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    Phenology is an indicator of plant response to the environment. In viticulture growth stages timing is important for site and cultivar selection, vineyard planning and cultural practices management. In the last years, autochthonous cultivars obtained an increased interest and, therefore, in this work we studied the phenological performances of Hungarian old varieties. The data recorded in 2012 were compared with the ones published 60 years ago. The examined genotypes were identified by SSR markers. Extremely high temperature and low precipitation occurred during the 2012 vintage. The uncommon weather conditions affected the length of the vegetation period less than expected. However, the time period between flowering and harvest decreased significantly. In general, minor varieties seem to be more sensitive to extreme conditions than international cultivars, according to their eno-carpological characteristics

    Dispatchable High-Power Wind Turbine Based on a Multilevel Converter with Modular Structure and Hybrid Energy Storage Integration

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    This paper presents a new multilevel converter solution with modular structure and hybrid energy-storage integration suitable to drive modern/future high-power medium-voltage wind turbines. The hybrid energy-storage integration means that part of the converter submodules are built with batteries and part of them with conventional capacitors. Since traditional wind turbines are non-dispatchable generators, the integration of an energy storage system could be beneficial in multiple ways as the wind power plant could provide stability support to the grid, improvement of the unit commitment and economic dispatch, and the power plant owner could increase his revenues in the electricity market. The capacitors of the proposed converter are responsible to transfer the power produced by the wind turbine to the grid, and the batteries are only charged/discharged with the mismatch between the power produced by the turbine and the power to be injected into the grid, considering a dispatchable operation where the power injected into the grid is different from the power generated by the turbine. The medium-voltage structure could be an interesting option to overcome problems related to high currents in modern/future high-power wind turbines resulting in more efficient, more compact and lighter solutions. Modular multilevel converters are suitable to handle medium-voltage levels and they allow for a straightforward integration of energy storage systems in a decentralized manner

    Characterization of the rabbit neonatal Fc receptor (FcRn) and analyzing the immunophenotype of the transgenic rabbits that overexpresses FcRn

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    The neonatal Fc receptor (FcRn) regulates IgG and albumin homeostasis, mediates maternal IgG transport, takes an active role in phagocytosis, and delivers antigen for presentation. We have previously shown that overexpression of FcRn in transgenic mice significantly improves the humoral immune response. Because rabbits are an important source of polyclonal and monoclonal antibodies, adaptation of our FcRn overexpression technology in this species would bring significant advantages. We cloned the full length cDNA of the rabbit FcRn alpha-chain and found that it is similar to its orthologous analyzed so far. The rabbit FcRn - IgG contact residues are highly conserved, and based on this we predicted pH dependent interaction, which we confirmed by analyzing the pH dependent binding of FcRn to rabbit IgG using yolk sac lysates of rabbit fetuses by Western blot. Using immunohistochemistry, we detected strong FcRn staining in the endodermal cells of the rabbit yolk sac membrane, while the placental trophoblast cells and amnion showed no FcRn staining. Then, using BAC transgenesis we generated transgenic rabbits carrying and overexpressing a 110 kb rabbit genomic fragment encoding the FcRn. These transgenic rabbits - having one extra copy of the FcRn when hemizygous and two extra copies when homozygous - showed improved IgG protection and an augmented humoral immune response when immunized with a variety of different antigens. Our results in these transgenic rabbits demonstrate an increased immune response, similar to what we described in mice, indicating that FcRn overexpression brings significant advantages for the production of polyclonal and monoclonal antibodies
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