Search results for "Gram"
showing 10 items of 9069 documents
Zvaigžņotā Debess: 2010/11, Ziema (210)
2010
Contents: “ZVAIGŅOTĀ DEBESS” FORTY YEARS AGO: Bursting Stars. J. Francman (abridged). Geodesists Help Renew the Spire of St. Peter’s Church. J. Klētnieks (abridged). DEVELOPMENTS in SCIENCE: The Solar Neutrino Problem. O. Smirnova. NEWS: At Last the Planet at the Star β Pictoris Is Imaged. A. Alksnis, Z. Alksne. SPACE RESEARCH and EXPLORATION: The Trail of an Asteroid Reveals a Recent Collision. A. Alksnis. INTERNATIONAL YEAR of ASTRONOMY 2009: International Year of Astronomy 2009 in Philately. The Rest of the World except Series EUROPA (concluded). J. Limansky. ACADEMIC STAFF of the UNIVERSITY of LATVIA: Assistant Professor in Physics Ojārs Šmits (24.04.1930.-14.03.1993.) of the Latvian Un…
Optimización de las propiedades de emulsión de betún para la estabilización de balasto
2017
Ballasted track, while providing economical and practical advantages, is associated with high costs and material consumption due to frequent maintenance. More sustainable alternatives to conventional ballasted trackbeds should therefore aim at extending its durability, particularly considering ongoing increases in traffic speed and loads. In this regard, the authors have investigated a solution consisting of bitumen stabilised ballast (BSB), designed to be used for new trackbeds as well as in reinforcing existing ones. This study presents the idea behind the technology and then focuses on a specific part of its development: the optimisation of bitumen emulsion properties and dosage in relat…
CoOx catalysts supported on alumina and alumina-baria: influence of the support on the cobalt species and their activity in NO reduction by C3H6 in l…
2003
Abstract CoO x catalysts (Co 1 and 3 wt.%) were prepared by incipient-wetness impregnation of the supports, Al 2 O 3 and Al 2 O 3 (80 wt.%)-BaO (20 wt.%), and calcined at 500 and 800 °C. The samples were characterized by X-ray diffraction (XRD) and BET techniques. H 2 -temperature programmed reduction (TPR) and UV-Vis diffuse reflectance spectroscopy (DRS) spectra were recorded with the aim to identify the different Co species formed. The presence of Co 2+ species tetrahedrally and octahedrally coordinated appears strongly influenced by the nature of the support and the cobalt content. Co 3 O 4 particles were detected after calcination at 500 °C, a successive treatment at 800 °C promotes th…
A model for the γN → ππN reaction
1995
We have studied the γN→ππN reaction using a model which includes N, Δ(1232), N*(1440) and N*(1520) intermediate baryonic states and the ρ-meson as intermediate ππ resonance. The model reproduces fairly well experimental cross sections below E γ = 800 MeV and invariant-mass distributions even at higher energies. One of the interesting findings of the study is that the γ N →N*(1520) → Δπ process is very important and interferes strongly with the dominant Δ-Kroll-Ruderman term to produce the experimental peak of the cross section.
Visible and near-infrared multispectral analysis of geochemically measured rock fragments at the Opportunity landing site in Meridiani Planum
2010
[1] We have used visible and near-infrared Panoramic Camera (Pancam) spectral data acquired by the Opportunity rover to analyze 15 rock fragments at the Meridiani Planum landing site. These spectral results were then compared to geochemistry measurements made by the in situ instruments Mossbauer (MB) and Alpha Particle X-ray Spectrometer (APXS) to determine the feasibility of mineralogic characterization from Pancam data. Our results suggest that dust and alteration rinds coat many rock fragments, which limits our ability to adequately measure the mineralogy of some rocks from Pancam spectra relative to the different field of view and penetration depths of MB and APXS. Viewing and lighting …
Bounce Rock-A shergottite-like basalt encountered at Meridiani Planum, Mars
2011
Additional co-authors: Thanasis ECONOMOU, Steven P. GOREVAN, Brian C. HAHN, Gostar KLINGELHOFER, Timothy J. McCOY, Harry Y. McSWEEN Jr, Douglas W. MING, Richard V. MORRIS, Daniel S. RODIONOV, Steven W. SQUYRES, Heinrich WANKE, Shawn P. WRIGHT, Michael B. WYATT, Albert S. YEN
Fe Mossbauer spectroscopy as a tool in astrobiology
2006
The element Fe and Fe-bearing minerals occur ubiquitously throughout the field of astrobiology. Cycling between the various oxidation states of Fe provides a source of energy available for life. Banded iron formations may record the rise of oxygenic photosynthesis. The distribution of Fe between Fe-bearing minerals and its oxidation states can help to characterize and understand ancient environments with respect to the suitability for life by constraining the primary rock type and the redox conditions under which it crystallized, the extent of alteration and weathering, the type of alteration and weathering products, and the processes and environmental conditions for alteration and weatheri…
Spectral, mineralogical, and geochemical variations across Home Plate, Gusev Crater, Mars indicate high and low temperature alteration
2009
Over the last ~3 years in Gusev Crater, Mars, the Spirit rover observed coherent variations in color, mineralogy, and geochemistry across Home Plate, an ~80 m-diameter outcrop of basaltic tephra. Observations of Home Plate from orbit and from the summit of Husband Hill reveal clear differences in visible/near-infrared (VNIR) colors between its eastern and western regions that are consistent with mineralogical compositions indicated by Mössbauer spectrometer (MB) and by Miniature Thermal Emission Spectrometer (Mini-TES). Pyroxene and magnetite dominate the east side, while olivine, nanophase Fe oxide (npOx) and glass are more abundant on the western side. Alpha Particle X-Ray Spectromet…
Analysis of the eigenfrequencies of the basalt machine parts by the FEM
2021
The aim of this paper was to carry out a theoretical (numerical) scientific research on the behavior of cast and recrystallized basalt, in order to use it as a material in the manufacture of structural elements of machine tools. A unitary methodology has been established for studying the eigenfrequency of structural elements for machine tools by the finite element method. Two basalt structural elements (beam type and plate type) were modeled, which were also made physically, and with the help of the COSMOS / Mark finite element program, the eigenfrequencies of the models was studied.
The Spirit Rover's Athena science investigation at Gusev Crater, Mars.
2004
The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.