1,672 research outputs found

    Function length as a tool for malware classification

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    The proliferation of malware is a serious threat to computer and information systems throughout the world. Antimalware companies are continually challenged to identify and counter new malware as it is released into the wild. In attempts to speed up this identification and response, many researchers have examined ways to efficiently automate classification of malware as it appears in the environment. In this paper, we present a fast, simple and scalable method of classifying Trojans based only on the lengths of their functions. Our results indicate that function length may play a significant role in classifying malware, and, combined with other features, may result in a fast, inexpensive and scalable method of malware classification.<br /

    THEORETICAL VALIDATION OF TEST RESULTS FOR THE PRESSURE DROP VALUES OF CIRCULAR PINS WITH A MAXIMUM LENGTH TO DIAMETER RATIO OF 3.0 USING EXISTING EQUATIONS AND TEST DATA FOR HEAT EXCHANGER APPLICATION

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    Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Pins are a very common type of extended surface used in the field of heat transfer; their main use being in the electronics field. In this report, the use of pins as an extended surface is considered for a Heat Exchanger application in the aerospace field. The Heat Exchanger uses forced convective heat transfer mechanism for the dissipation of heat and the implicated fluid is air. For this application the pin layout and design is completely unique in that the pin’s maximum length to diameter ratio is 3.0 and the layout of the pins produces an X T value of 7, which has not been explored in any previous work. The Length: Diameter ratio of these new pins is very small when compared to the Length: Diameter ratios of tubes currently used in heat exchangers to enhance heat transfer. Moreover, the distance between the pins in this arrangement is much greater than those for the tubes. Testing has been performed on this pin design and the theoretical validation of those test results is one of the main aspects discussed in this report. Due to the innovative nature of the pin designs, there is insufficient existing test data or established equations that can be used. Assumptions are made in order to be able to apply the current equations for pressure drop calculations with valid justifications. The theoretical results for the total pressure drop show an average deviation of 6% from the test results for mass flow rates between 0.14 kg/s and 0.36 kg/s. The maximum pressure drop was found to be caused by the pins and it was in the range of 89%-91%of the total. In this article, the limitations of existing equations are discussed and the gap in the theoretical knowledge regarding novel pin designs is highlighted.mp201

    Alice: The Rosetta Ultraviolet Imaging Spectrograph

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    We describe the design, performance and scientific objectives of the NASA-funded ALICE instrument aboard the ESA Rosetta asteroid flyby/comet rendezvous mission. ALICE is a lightweight, low-power, and low-cost imaging spectrograph optimized for cometary far-ultraviolet (FUV) spectroscopy. It will be the first UV spectrograph to study a comet at close range. It is designed to obtain spatially-resolved spectra of Rosetta mission targets in the 700-2050 A spectral band with a spectral resolution between 8 A and 12 A for extended sources that fill its ~0.05 deg x 6.0 deg field-of-view. ALICE employs an off-axis telescope feeding a 0.15-m normal incidence Rowland circle spectrograph with a concave holographic reflection grating. The imaging microchannel plate detector utilizes dual solar-blind opaque photocathodes (KBr and CsI) and employs a 2 D delay-line readout array. The instrument is controlled by an internal microprocessor. During the prime Rosetta mission, ALICE will characterize comet 67P/Churyumov-Gerasimenko's coma, its nucleus, and the nucleus/coma coupling; during cruise to the comet, ALICE will make observations of the mission's two asteroid flyby targets and of Mars, its moons, and of Earth's moon. ALICE has already successfully completed the in-flight commissioning phase and is operating normally in flight. It has been characterized in flight with stellar flux calibrations, observations of the Moon during the first Earth fly-by, and observations of comet Linear T7 in 2004 and comet 9P/Tempel 1 during the 2005 Deep Impact comet-collision observing campaignComment: 11 pages, 7 figure

    A combined study of heat and mass transfer in an infant incubator with an overhead screen

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    The main objective of this study is to investigate the major physical processes taking place inside an infant incubator, before and after modifications have been made to its interior chamber. The modification involves the addition of an overhead screen to decrease radiation heat losses from the infant placed inside the incubator. The present study investigates the effect of these modifications on the convective heat flux from the infant’s body to the surrounding environment inside the incubator. A combined analysis of airflow and heat transfer due to conduction, convection, radiation and evaporation has been performed, in order to calculate the temperature and velocity fields inside the incubator before and after the design modification. Due to the geometrical complexity of the model, Computer-Aided Design (CAD) applications were used to generate a computer-based model. All numerical calculations have been performed using the commercial Computational Fluid Dynamics (CFD) package FLUENT, together with in-house routines used for managing purposes and User-Defined Functions (UDFs) which extend the basic solver capabilities. Numerical calculations have been performed for three different air inlet temperatures: 32, 34 and 36ºC. The study shows a decrease of the radiative and convective heat losses when the overhead screen is present. The results obtained were numerically verified as well as compared with results available in the literature from investigations of dry heat losses from infant manikins

    Pairing of charged particles in a quantum plasmoid

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    We study a quantum spherically symmetric object which is based on radial plasma oscillations. Such a plasmoid is supposed to exist in a dense plasma containing electrons, ions, and neutral particles. The method of creation and annihilation operators is applied to quantize the motion of charged particles in a self-consistent potential. We also study the effective interaction between oscillating particles owing to the exchange of a virtual acoustic wave, which is excited in the neutral component of plasma. It is shown that this interaction can be attractive and result in the formation of ion pairs. We discuss possible applications of this phenomenon in astrophysical and terrestrial plasmas.Comment: 17 pages, no figures, two columns, LaTeX2e; paper was significantly revised; title was changed; 16 new references were included; the discussion on ion-acoustic waves was added to Sec. 2; Secs. 3 and 4 were shortened; a more detailed discussion was added to Sec. 7; accepted for publication to J.Phys.

    Rosetta-Alice Observations of Exospheric Hydrogen and Oxygen on Mars

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    The European Space Agency's Rosetta spacecraft, en route to a 2014 encounter with comet 67P/Churyumov-Gerasimenko, made a gravity assist swing-by of Mars on 25 February 2007, closest approach being at 01:54UT. The Alice instrument on board Rosetta, a lightweight far-ultraviolet imaging spectrograph optimized for in situ cometary spectroscopy in the 750-2000 A spectral band, was used to study the daytime Mars upper atmosphere including emissions from exospheric hydrogen and oxygen. Offset pointing, obtained five hours before closest approach, enabled us to detect and map the HI Lyman-alpha and Lyman-beta emissions from exospheric hydrogen out beyond 30,000 km from the planet's center. These data are fit with a Chamberlain exospheric model from which we derive the hydrogen density at the 200 km exobase and the H escape flux. The results are comparable to those found from the the Ultraviolet Spectrometer experiment on the Mariner 6 and 7 fly-bys of Mars in 1969. Atomic oxygen emission at 1304 A is detected at altitudes of 400 to 1000 km above the limb during limb scans shortly after closest approach. However, the derived oxygen scale height is not consistent with recent models of oxygen escape based on the production of suprathermal oxygen atoms by the dissociative recombination of O2+.Comment: 17 pages, 8 figures, accepted for publication in Icaru

    Dissociation constants and thermodynamic properties of amino acids used in CO2 absorption from (293 to 353) K

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    The second dissociation constants of the amino acids βalanine, taurine, sarcosine, 6-aminohexanoic acid, DL-methionine, glycine, L-phenylalanine, and L-proline and the third dissociation constants of L-glutamic acid and L-aspartic acid have been determined from electromotive force measurements at temperatures from (293 to 353) K. Experimental results are reported and compared to literature values. Values of the standard state thermodynamic properties are derived from the experimental results and compared to the values of commercially available amines used as absorbents for CO 2 capture.

    Йосиф Конрадович Пачоський: історіографія проблеми

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    Проаналізовано наукові, науково-популярні, публіцистичні, літературні джерела щодо біографії і наукової діяльності Й.К. Почоського, розділені на три періоди: перший — дореволюційний період вивчення життєвого шляху та наукової діяльності вченого (1882—1917), другий — радянський (1917—1989), третій — сучасний (1989 р.). Окрім вітчизняних, висвітлено праці дослідників із Польщі.Проанализированы научные, научно-популярные, публицистические, литературные источники по биографии и научной деятельности И.К.Пачоского, разделенные на три периода: первый — дореволюционный период изучения жизненного пути и научной деятельности ученого (1882—1917), второй советский (1917—1989), третий — современный (с 1989 г. ). Кроме отечественных, освещены работы исследователей из Польши.The paper contains analysis of scientific, popular-scientific, publicistic and literary sources on the scientific biography of I.K. Pachosky, divided in the three periods: first — pre-revolutionary (1882—1917), second — soviet (1917—1989), third — contemporary (1989 and on). Apart from national scientists, works of scientists from Poland also included
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