2,877 research outputs found
Heat transfer from rough surfaces: some considerations on the assumption of logarithmic velocity and temperature profiles
Parametric thermohydraulic calculations for advanced pressurized water reactors with the code HADA-2
Rotationally resolved spectroscopy of (20000) Varuna in the near-infrared
Models of the escape and retention of volatiles by minor icy objects exclude
any presence of volatile ices on the surface of TNOs smaller than ~1000km in
diameter at the typical temperature in this region of the solar system, whereas
the same models show that water ice is stable on the surface of objects over a
wide range of diameters. Collisions and cometary activity have been used to
explain the process of surface refreshing of TNOs and Centaurs. These processes
can produce surface heterogeneity that can be studied by collecting information
at different rotational phases. The aims of this work are to study the surface
composition of (20000)Varuna, a TNO with a diameter ~650km and to search for
indications of rotational variability. We observed Varuna during two
consecutive nights in January 2011 with NICS@TNG obtaining a set of spectra
covering the whole rotation period of Varuna. After studying the spectra
corresponding to different rotational phases, we did not find any indication of
surface variability. In all the spectra, we detect an absorption at 2{\mu}m,
suggesting the presence of water ice on the surface. We do not detect any other
volatiles on the surface, although the S/N is not high enough to discard their
presence. Based on scattering models, we present two possible compositions
compatible with our set of data and discuss their implications in the frame of
the collisional history of the Kuiper Belt. We find that the most probable
composition for the surface of Varuna is a mixture of amorphous silicates,
complex organics, and water ice. This composition is compatible with all the
materials being primordial. However, our data can also be fitted by models
containing up to a 10% of methane ice. For an object with the characteristics
of Varuna, this volatile could not be primordial, so an event, such as an
energetic impact, would be needed to explain its presence on the surface.Comment: 6 pages, 5 figures, to be published in A&
Measurements of density and of thermal expansion coefficient of sodium tetraborate (borax)-UOâ‚‚ and of sodium metaborate-UOâ‚‚ solutions
Heat transfer for turbulent flow of helium or hydrogen in a tube at high temperatures: evaluation with the method of Petukhov
Heat transfer and friction coefficients for air flow in a smooth annulus; results of a recent experiment and comparison with previous correlations
Some considerations on tritium control in a helium cooled ceramic blanket for the NET reactor
Aurora 3d Presentation Dalam Pembelajaran Bangun Ruang Sisi Lengkung Di Kelas IX SMPN 24 Banjarmasin
Software Aurora 3D Presentation yang merupakan media pembelajaran interaktif yang diadaptasi dari software sebelumnya yaitu Microsoft Power Point. Hanya saja, Aurora 3D Presentation menyajikan kemudahan dalam penggunaan animasi presentasi baik dua atau tiga dimensi. Aurora 3D Presentation dipilih dikarenakan software yang berbasis presenatsi dan tidak terlalu mengurangi peranan guru dalam proses pembelajaran, selain itu software ini memiliki fitur-fitur tiga dimensi yang mudah digunakan serta mendukung materi yang akan diajarkan atau diteliti yaitu bangun ruang sisi lengkung. Tujuan dari penelitian ini adalah untuk mengetahui perbedaan hasil belajar antara pembelajaran dengan menggunakan media pembelajaran interaktif Aurora 3D Presentation dan model pembelajaran konvensional pada materi Bangun Ruang Sisi Lengkung di Kelas IX SMPN 24 Banjarmasin tahun pelajaran 2014/2015.Penelitian kali ini menggunakan metode eksperimen dengan jenis penelitian lapangan dan pendekatan kuantitatif. Populasi penelitian ini adalah kelas IX.A, IX.B, IX.C, IX.D, IX.E, dan IX.B SMPN 24 Banjarmasin yang dibagi menjadi dua kelompok atau dua kelas. Yaitu kelas eksperimen (kelompok uji coba) dan kelas kontrol (kelompok kendali) yang ditentukan melalui teknik Sample Random Sampling sehingga diperoleh kelas eksperimen adalah kelas IX.C dan kelas kontrol adalah kelas IX.A. Pada kedua kelas tersebut akan diberikan tes kemampuan awal, pre test, dan post test.Berdasarkan uji t pada hasil belajar siswa melalui post test, diperoleh harga thitung = 2.185dan ttabel = 2.000. Karena -ttabel ≤ thitung ≤ ttabel, maka Ha diterima dan H0 ditolak, kemudian disimpulkan bahwa terdapat perbedaan hasil belajar yang signifikan antara pembelajaran dengan menggunakan media pembelajaran interaktif Aurora 3D Presentation dan model pembelajaran konvensional pada materi bangun ruang sisi lengkung di kelas IX SMPN 24 Banjarmasin tahun pelajaran 2014/2015
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