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  • 1
    Electronic Resource
    Electronic Resource
    Grains accretion processes in a proto-planetary nebula (1977)
    Springer
    Astrophysics and space science 48 (1977), S. 79-87 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Some mechanisms which are expected to produce the growth of dust grains in the protosolar nebula are studied during the isothermal and the adiabatic phase of the gravitational collapse. Owing to the low sticking efficiency in the grain-grain collisions and also to the impossibility of gas capture by solid particles in the physical environment considered, the main result is the production in about 106 yr of a set of particles similar in mass. The obtained mass limit (10−8–10−9 g) depends on the physical properties of the grains, and seems to be independent of the turbulence model used for the gas motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00643041
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  • 2
    Electronic Resource
    Electronic Resource
    Time evolution of grains in the protosolar nebula (1980)
    Springer
    Earth, moon and planets 22 (1980), S. 47-61 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The problem of the motion of grains in the protosolar nebula is discussed. Time scales of the vertical and radial displacement are computed. The structure of the dust disk that can be formed is discussed in the framework of different protosolar nebula models. The results obtained under the hypothesis of quiescience of the gas component are compared with those in presence of a fully developed turbulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00896866
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  • 3
    Electronic Resource
    Electronic Resource
    Multivariate classification methods in planetary sciences (1992)
    Springer
    Earth, moon and planets 59 (1992), S. 141-152 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In this paper the problem of the classification of natural samples is discussed. An updated version of the G-mode multivariate statistical method for the classification of natural samples, applicable to a wide range of research fields, is discussed in this paper. This method allows an automatic classification in terms of homogeneous taxonomic units, without any a priori knowledge of the taxonomic structure of the natural observations; it provides informations on the different levels of classification present in the data set under study (classes and subclasses), on the level of information residing in each variable, on the level of similarity and/or difference among homogeneous classes. An earlier version of this method has been widely applied in planetary sciences, astrophysics and geological sciences. The authors give here a resumé of the most interesting results obtained in these different research fields, from the geochemistry of lunar samples to asteroids taxonomy to remote sensing of planetary surfaces. This method is extremely reliable and versatile, and it is suggested that its use be widespread whenever the problem of the classification of a large set of natural samples occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058728
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  • 4
    Electronic Resource
    Electronic Resource
    Classification of lunar rocks and glasses by a new statistical technique (1976)
    Springer
    Earth, moon and planets 16 (1976), S. 175-190 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Реφерат Применен и описан новый многомерный статистический метод выделения однородных классов объектов. Обсуждаются результаты, полученные при анализе лунных пород и стекол. Лунные породы находятся в следующих генетических соотношениях: пироксенитовый материал и анортозиты являются крайними членами дифференциации пород, высокотитанистые морские базальты, нориты и континентальные базальты занимают среднее положение. Состав стекол отражает состав пород с некоторыми частичными особенностями. Например, гранитный материал присутствует только в стеклах и имеет вероятно остаточное происхождение. Взаимоотношения между выделенными однородными классами пород и стекод обсуждаются с точки зрения эводюции лунной коры
    Notes: Abstract A new multivariate statistical technique have been developed for detection of populations groupings in data arrays. General characteristics of the method are described. Results obtained analyzing lunar rocks and glasses are discussed. Lunar rocks lie in a genetically related sequence: pyroxenitic mantle materials produce mare type basalts; anorthositic rocks are the most distant members of the differentiation; noritic, hi-Ti and high KREEP basalts materials appear to be intermediate products. Lunar glasses parallel the overall behaviour of rocks, with some peculiar local characteristics. Granitic materials are present only as glasses, suggesting an origin as residuals. Links between several identified classes are discussed in terms of the evolution of the lunar crust.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00648052
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  • 5
    Electronic Resource
    Electronic Resource
    Grains accretion processes in a protoplanetary nebula: Effects of the presence of liquid drops (1978)
    Springer
    Earth, moon and planets 18 (1978), S. 65-76 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The temporal behaviour of the mass distribution function of iron solid and/or liquid grains is studied in the inner regions of the solar nebula during its gravitational collapse. At distances from the centre of the nebula equal to 0.2 AU, 0.5 AU and 0.7 AU a mass limit for the accretionary process equal, respectively, to 17.6 g, 5.2 g and 3×10−3 g is obtained in a reasonable time interval. The importance of a ‘drop phase’ during the growth of the particles and of the ‘sedimentation’ of the grains during the ‘disk phase’ is underlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00896698
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  • 6
    Electronic Resource
    Electronic Resource
    The statistical approach to the study of planetary surfaces (1980)
    Springer
    Earth, moon and planets 22 (1980), S. 293-304 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A review of the statistical methods and their application to the planetary sciences is presented. Univariate and multivariate methods are used, with different sophistication levels, to the search for the relationships between samples and/or variables belonging to data coming from space missions. Some numerical expressions, which summarize the information in mathematical terms, such as the mean, the variance, and the coefficient of variation are the best known and most widely used to perform a preliminar analysis of a data set. Techniques of regression and trend analysis allow us to compare the reciprocal behaviour of different variables, each treated as an univariate one. Making inferences about the statistical parameters permits the determination of the range of the parameter values which are consistent with the information contained in the samples. Multivariate analysis is devoted to the study of multidimensional (i.e., of several variables) distributions of the samples. The analysis of the variance is a multivariate technique useful in investigating whether or not two or more groups of multivariate observations come from populations with the same mean value. The discriminant analysis provides a function for classifying multivariate observations into groups. One of the simpler factorial techniques is the principal-components method in which the original variables are associated in a ‘typical’ form that can be interpreted in terms of a genetic process. TheR-mode analysis is useful in identifying the number of important variables. TheQ-mode analysis permits us to group the observations providing clusters of samples. TheG-mode method, where the original multivariate distribution is transformed in a ‘univariate quasi-Gaussian’ distribution, can be applied to identify homogenous group of samples and to classify new samples on the basis of the general groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01259286
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  • 7
    Electronic Resource
    Electronic Resource
    Modelling of surface ground deformations in the Phlegraean Fields volcanic area, Italy (1984)
    Springer
    Bulletin of volcanology 47 (1984), S. 321-330 
    Details
    ISSN: 1432-0819
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A preliminary finite elements model of the ground deformations observed at Phlegraean Fields is proposed. The model assumes an oblate-spheroid magma chamber at the depth of 5.4 km with major semiaxis of 1.5 km and minor semiaxis of 0.75 km. The dimensions of the magma chamber have been evaluated by using a thermal model based on the assumptions that a progressively cooling huge magmatic body is responsible for the volcanic activity at Phlegraean Fields in the last 35,000 years. Surface deformations caused by an over-pressure of 30 MPa in the magma chamber have been calculated. Constant, and temperature-dependent elastic parameters of the surrounding medium have been considered. Vertical displacements of the order of those presently observed at Phlegraean Fields can be obtained only with temperature-dependent elastic properties of the medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01961563
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  • 8
    Electronic Resource
    Electronic Resource
    A Moon orbiting observatory for the measurement of the elemental and isotopic composition in the primary cosmic radiation (1994)
    Springer
    Astrophysics and space science 220 (1994), S. 131-147 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a project for the measurement of elemental composition of the primary cosmic radiation to be performed by a space observatory orbiting around the Moon. The absence of atmosphere and the low intrinsic magnetic field of the Moon give access to the very low energy component of the cosmic radiation, allowing the search for rare events. The quest for antinuclei, the determination of the lunar lepton albedo and the abundance measurement of galactic radioactive clocks (Be10, C14, Al26) are the major tasks of the ANTARES apparatus (ANTimatter Assessment RESearch). We report details of the instrument design, the expected performance for single detectors, their capability to accomplish the proposed measurements and the characteristics of the space mission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00628083
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  • 9
    Electronic Resource
    Electronic Resource
    A classification of lunar rock and glass samples using theG-mode central method (1980)
    Springer
    Earth, moon and planets 22 (1980), S. 305-322 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We have used theG-mode central method to classify sets of major oxide chemical data of lunar rocks (163 averages) and lunar glasses (921 separate analyses). These data were selected from the Lunar Data Base using the following criteria: (1) the amount of SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, and K2O were measured by the same group of investigators and (2) the sum of these 8 major oxides was in the range 97.0–103.0 wt.% for the rocks and 99.0–101.0 for the glasses. TheG-mode central method attempts to recognize homogeneous sets or groups of samples within a raw data matrix. The original multivariate distribution is reduced to a set ofG values which follow a ‘quasi-Gaussian univariate’ distribution. Each of the homogenous groups consists of those samples that can be described by a specific normal distribution of the computedG values. We have followed previous suggestions and have not yet experimented with the effects of variations in estimates of precision, the nature of the distribution(s), or the influence of percentage formation on the recognition of homogenous groups. Fifteen groups of lunar rocks have been recognized but three of these groups are very small and certainly not homogeneous. All eight variables contribute to the recognition of the 12 retained groups (151 averages) with TiO2−Al2O3−FeO being the most effective ternary subset for the recognition and definition of these groups. A combination ofQ-mode cluster analysis (using all 8 major oxides and cos θ as the measure of similarity) and spatial position in the TiO2−Al2O3−FeO ternary allowed recognition of five families of the 151 retained lunar rock averages. Oxide wt.% and cation normative mean vectors are given for each of the 12 groups. We have assigned names to each of the families on the basis of comparisons with published information but these names are to be considered as descriptive andnot genetic. A total of 8 families and 16 groups of lunar glasses have been recognized and vector means for the oxide wt.% and cation percentage normative components are given along with the number of samples in each group and the percentage of the total number of retained samples (885) accounted for by each group. Again, names used to describe each group should not be considered as having genetic significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01259287
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  • 10
    Electronic Resource
    Electronic Resource
    Grains accretion processes in a protoplanetary nebula: Conducting and insulating materials (1975)
    Springer
    Astrophysics and space science 33 (1975), S. 369-384 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a previous work the authors estimated cross-sections for constructive and destructive collisions (‘constructive’ and ‘destructive’ cross-sections) related to silica grains embedded in a protoplanetary nebula. The outstanding point of the problem has induced the authors to examine more closely the physical conditions in which the accretion processes occur, and their dependence on the materials, by which the particles are probably made. In this paper the interaction processes among conducting grains (iron, graphite) and among the insulating (silica) ones have been considered. The following results have been obtained: (1) insulating grains have smaller constructive crossections than conducting; and (2) conducting grains show very large cross-sections for masses up to about 10−9 g.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00640106
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