261 research outputs found

    Hot Rocks! Near-Infrared Reflectances (and Emissivities) or Rocks at Venus Surface Temperatures

    Get PDF
    Venus surface can be viewed in emission through a few near-infrared (NIR) spectral windows (1 m) in its relatively opaque atmosphere [1]. Venus surface shows NIR emissivities that correlate with surface geology [2-4], and these emissivity variations are interpreted as differences in surface rock type (mafic vs. silicic) and/or extent of weathering (Fe2+ silicates vs. Fe3+-oxide-coated). To understand and quantify the observed variations in NIR emissivity, high-temperature (T) emissivity can be measured directly [5,6]. For example, emissivities of basalts in the wavelength range 0.85 1.2 m are ~0.95 [5-8]. This can be tested by measureing reflectance, because Kirchoffs Law holds that emissivity (e) = 1 reflectance (r). The r of basalt in the NIR is ~0.05 [o] consistent with a NIR e of ~0.95 [5-8]. High-T NIR es of silicic igneous rocks (granitic, rhyolite) have been reported to be 0.8-0.9 [5,6], which is inconsistent with r values of 0.3-0.8 of such rocks at 25C [9,10]. However, these measurements have been updated [7,8] and are consistent with the results here (see below and Fig. 3)

    TANGGUNG JAWAB HUKUM TERHADAP PENYEDIA BARANG DAN JASA DALAM PELAKSANAAN JASA KONSTRUKSI BERDASARKAN UNDANG-UNDANG NOMOR 2 TAHUN 2017 TENTANG JASA KONSTRUKSI

    Get PDF
    Penelitian ini dilakukan dengan tujuan untuk mengetahui bagaimana Tanggung jawab Hukum penyedia barang dan jasa secara administratif dan bagaimana Tanggung jawab Hukum penyedia barang dan jasa dilaksanakan secara fisik konstruktif. Dwengan menggunakan metode penelitian yuridis normatif, disimpulkan: 1. Pelaksanaan jasa konstruksi, penyedia jasa harus memiliki standart hukum/peraturan yang berlaku secara administratif dalam menyediakan barang dan jasa, karena mempunyai peran yang penting dalam pencapaian pembangunan nasional. Administratif yang dimaksud adalah mulai dari tahap pelelangan sampai dengan tahap pelaksanaan, meliputi kelengkapan dokumen sesuai standart peraturan yang berlaku. Persyaratan kelengkapan dokumen tersebut adalah bagian dari tanggung jawab serta bukti hukum pelaksanaan kegiatan. 2. Pelakasanaan kontrak khususnya pembangunan proyek, tanggung jawab pihak penyedia jasa atau kontraktor adalah melaksanakan pekerjaan konstruksi sesuai dengan instruksi dari pihak pemberi tugas atau dalam kontrak ini disebut dengan Pejabat Pembuat Komitmen (PPK). Pihak kontraktor bertanggung jawab untuk melaksanakan pekerjaan tersebut sesuuai dengan kontrak atau syarat-syarat yang telah ditetapkan berdasarkan hasil negosiasi awal yang telah disepakati. Karena dilapangan seringkali ditemukan perjanjian antara pihak pengguna jasa dan penyedia jasa/kontraktor yang tidak sesuai dan hal ini perlu dihindari.Kata kunci: Tanggung Jawab Hukum, Penyedia Barang dan Jasa, Konstruks

    Phase Equilibria Modeling of Low-grade Metamorphic Martian Rocks

    Get PDF
    Hydrous phases have been identified to be a significant component of martian mineralogy. Particularly prehnite, zeolites, and serpentine are evidence for low‐grade metamorphic reactions at elevated temperatures in mafic and ultramafic protoliths. Their presence suggests that at least part of the martian crust is sufficiently hydrated for low‐grade metamorphic reactions to occur. A detailed analysis of changes in mineralogy with variations in fluid content and composition along possible martian geotherms can contribute to determine the conditions required for subsurface hydrous alteration, fluid availability and rock properties in the martian crust. In this study, we use phase equilibria models to explore low‐grade metamorphic reactions covering a pressure‐temperature range of 0‐0.5 GPa and 150‐450 °C for several martian protolith compositions and varying fluid content. Our models replicate the detected low‐grade metamorphic/hydrothermal mineral phases like prehnite, chlorite, analcime, unspecified zeolites, and serpentine. Our results also suggest that actinolite should be a part of lower‐grade metamorphic assemblages, but actinolite may not be detected in reflectance spectra for several reasons. By gradually increasing the water content in the modeled whole rock composition, we can estimate the amount of water required to precipitate low‐grade metamorphic phases. Mineralogical constraints do not necessarily require an elevated geothermal gradient for the formation of prehnite. However, restricted crater excavation depths even for large impact craters are not likely sampling prehnite along colder gradients, either suggesting a geotherm of ~ 20 °C/km in the Noachian or an additional heat source such as hydrothermal or magmatic activity

    An original application of image recognition based location in complex indoor environments

    Get PDF
    This paper describes the first results of an image recognition based location (IRBL) for a mobile application focusing on the procedure to generate a database of range images (RGB-D). In an indoor environment, to estimate the camera position and orientation, a prior spatial knowledge of the surroundings is needed. To achieve this objective, a complete 3D survey of two different environments (Bangbae metro station of Seoul and the Electronic and Telecommunications Research Institute (ETRI) building in Daejeon, Republic of Korea) was performed using a LiDAR (Light Detection and Ranging) instrument, and the obtained scans were processed to obtain a spatial model of the environments. From this, two databases of reference images were generated using specific software realised by the Geomatics group of Politecnico di Torino (ScanToRGBDImage). This tool allows us to generate synthetically different RGB-D images centred in each scan position in the environment. Later, the external parameters (X, Y, Z, ω, ϕ, and κ) and the range information extracted from the retrieved database images are used as reference information for pose estimation of a set of acquired mobile pictures in the IRBL procedure. In this paper, the survey operations, the approach for generating the RGB-D images, and the IRB strategy are reported. Finally, the analysis of the results and the validation test are described

    A review of volatiles in the Martian interior

    Get PDF
    Multiple observations from missions to Mars have revealed compelling evidence for a volatile-rich Martian crust. A leading theory contends that eruption of basaltic magmas was the ultimate mechanism of transfer of volatiles from the mantle toward the surface after an initial outgassing related to the crystallization of a magma ocean. However, the concentrations of volatile species in ascending magmas and in their mantle source regions are highly uncertain. This work and this special issue of Meteoritics & Planetary Science summarize the key findings of the workshop on Volatiles in the Martian Interior (Nov. 3–4, 2014), the primary open questions related to volatiles in Martian magmas and their source regions, and the suggestions of the community at the workshop to address these open questions
    corecore