Session 4: Other fields of applicationhttp://hdl.handle.net/10256/6352017-05-29T21:16:20Z2017-05-29T21:16:20ZGrain size analyses in tin-lead glazes based on 2d-sectionsSchwedt, A.Buxeda i Garrigós, JaumeMadrid Fernández, Marisolhttp://hdl.handle.net/10256/6912012-11-30T07:34:04Z2005-10-01T00:00:00ZGrain size analyses in tin-lead glazes based on 2d-sections
Schwedt, A.; Buxeda i Garrigós, Jaume; Madrid Fernández, Marisol
Mateu i Figueras, Glòria; Barceló i Vidal, Carles
A problem in the archaeometric classification of Catalan Renaissance pottery is the fact, that
the clay supply of the pottery workshops was centrally organized by guilds, and therefore
usually all potters of a single production centre produced chemically similar ceramics.
However, analysing the glazes of the ware usually a large number of inclusions in the glaze is
found, which reveal technological differences between single workshops. These inclusions
have been used by the potters in order to opacify the transparent glaze and to achieve a white
background for further decoration.
In order to distinguish different technological preparation procedures of the single workshops,
at a Scanning Electron Microscope the chemical composition of those inclusions as well as
their size in the two-dimensional cut is recorded. Based on the latter, a frequency distribution
of the apparent diameters is estimated for each sample and type of inclusion.
Following an approach by S.D. Wicksell (1925), it is principally possible to transform the
distributions of the apparent 2D-diameters back to those of the true three-dimensional bodies.
The applicability of this approach and its practical problems are examined using different
ways of kernel density estimation and Monte-Carlo tests of the methodology. Finally, it is
tested in how far the obtained frequency distributions can be used to classify the pottery
2005-10-01T00:00:00ZInterpretation of wind components as compositional variablesBuenestado Caballero, PabloJarauta Bragulat, EusebioHervada i Sala, Carmehttp://hdl.handle.net/10256/6902012-06-28T12:30:36Z2005-10-01T00:00:00ZInterpretation of wind components as compositional variables
Buenestado Caballero, Pablo; Jarauta Bragulat, Eusebio; Hervada i Sala, Carme
Mateu i Figueras, Glòria; Barceló i Vidal, Carles
The classical statistical study of the wind speed in the atmospheric surface layer is made
generally from the analysis of the three habitual components that perform the wind data,
that is, the component W-E, the component S-N and the vertical component,
considering these components independent.
When the goal of the study of these data is the Aeolian energy, so is when wind is
studied from an energetic point of view and the squares of wind components can be
considered as compositional variables. To do so, each component has to be divided by
the module of the corresponding vector.
In this work the theoretical analysis of the components of the wind as compositional
data is presented and also the conclusions that can be obtained from the point of view of
the practical applications as well as those that can be derived from the application of
this technique in different conditions of weather
2005-10-01T00:00:00ZCompositional analysis of archaeological glassesBaxter, M.J.Beardah, C.C.Freestone, I.C.http://hdl.handle.net/10256/6882012-06-28T12:30:36Z2005-10-01T00:00:00ZCompositional analysis of archaeological glasses
Baxter, M.J.; Beardah, C.C.; Freestone, I.C.
Mateu i Figueras, Glòria; Barceló i Vidal, Carles
At CoDaWork'03 we presented work on the analysis of archaeological glass composi-
tional data. Such data typically consist of geochemical compositions involving 10-12
variables and approximates completely compositional data if the main component, sil-
ica, is included. We suggested that what has been termed `crude' principal component
analysis (PCA) of standardized data often identi ed interpretable pattern in the data
more readily than analyses based on log-ratio transformed data (LRA). The funda-
mental problem is that, in LRA, minor oxides with high relative variation, that may
not be structure carrying, can dominate an analysis and obscure pattern associated
with variables present at higher absolute levels. We investigate this further using sub-
compositional data relating to archaeological glasses found on Israeli sites. A simple
model for glass-making is that it is based on a `recipe' consisting of two `ingredients',
sand and a source of soda. Our analysis focuses on the sub-composition of components
associated with the sand source. A `crude' PCA of standardized data shows two clear
compositional groups that can be interpreted in terms of di erent recipes being used at
di erent periods, re
ected in absolute di erences in the composition. LRA analysis can
be undertaken either by normalizing the data or de ning a `residual'. In either case,
after some `tuning', these groups are recovered. The results from the normalized LRA
are di erently interpreted as showing that the source of sand used to make the glass
di ered. These results are complementary. One relates to the recipe used. The other
relates to the composition (and presumed sources) of one of the ingredients. It seems
to be axiomatic in some expositions of LRA that statistical analysis of compositional
data should focus on relative variation via the use of ratios. Our analysis suggests that
absolute di erences can also be informative
2005-10-01T00:00:00Z