1,217 research outputs found
Exchangeable Random Networks
We introduce and study a class of exchangeable random graph ensembles. They
can be used as statistical null models for empirical networks, and as a tool
for theoretical investigations. We provide general theorems that carachterize
the degree distribution of the ensemble graphs, together with some features
that are important for applications, such as subgraph distributions and kernel
of the adjacency matrix. These results are used to compare to other models of
simple and complex networks. A particular case of directed networks with
power-law out--degree is studied in more detail, as an example of the
flexibility of the model in applications.Comment: to appear on "Internet Mathematics
Brief communication: Using averaged soil moisture estimates to improve the performances of a regional-scale landslide early warning system
We communicate the results of a preliminary investigation aimed at
improving a state-of-the-art RSLEWS (regional-scale landslide early
warning system) based on rainfall thresholds by integrating mean
soil moisture values averaged over the territorial units of the
system. We tested two approaches. The simplest can be easily applied
to improve other RSLEWS: it is based on a soil moisture threshold
value under which rainfall thresholds are not used because
landslides are not expected to occur. Another approach deeply
modifies the original RSLEWS: thresholds based on antecedent
rainfall accumulated over long periods are substituted with soil
moisture thresholds. A back analysis demonstrated that both
approaches consistently reduced false alarms, while the second
approach reduced missed alarms as well
The vulnerability assessment of current buildings by a macroseismic approach derived from the EMS-98 scale
A hierarchical family of Damage Probability Matrices (DPM) has been derived in this
paper from the ones implicitly contained in the EMS-98 Macroseismic Scale for 6
vulnerability classes. To this aim the linguistic definitions provided by the scale, and the
associated fuzzy sub-sets of the percentage of buildings, have been completed according to
reliable hypotheses.
A parametric representation of the corresponding cumulative probability distributions
is moreover provided, through a unique parameter: a vulnerability index variable in the range
from 0 to 1 and independent of the macroseismic intensity. Finally, an innovative
macroseismic approach allowing the vulnerability analysis of building typologies is defined
within the European Macroseismic Scale (EMS-98) and qualitatively related to the
vulnerability classes. Bayes’ theorem allows the upgrading of the frequencies when further
data about the built-environment or specific properties of the buildings are available, allowing
the identification of a different behaviours with respect to the one generally considered for the
typology. Fuzzy measures of any damage function can be derived, using parametric or nonparametric
damage probability matrices. For every result of the seismic analysis, the
procedure allows supply to the user of the final uncertainty connected with the
aforementioned fuzzy relation between the probability of the damage grade, the
macroseismic intensity and the vulnerability classes
Seismic vulnerability of churches in Faial and Pico islands, Azores
Earthquakes represent one of the main cause of serious damage and loss of historic and architectural heritage. Interventions to preserve these building should start with a careful knowledge and assessment of their seismic vulnerability, in order to support any needed retrofitting and strengthening measures.
This paper proposes a procedure to register and diagnose of the level of damage on churches after the occurrence of an earthquake, and also to assess the seismic vulnerability of this type of construction. This procedure was applied to sixteen churches in the Azores islands which were hit by the July 9th 1998 earthquake.
Belfries of church towers are elements with a particular seismic vulnerability. For this reason, and based on the Italian methodology proposed by the Linee Guida (2006), it is applied to belfries of two churches from Pico (Azores), a simplified mechanical model for assessment of seismic vulnerability of this type of structures
VULNERABILITY ASSESSMENT OF DWELLING BUILDINGS
Risk is defined as the potential economic, social and environmental consequences of hazardous events that may occur in a specified area unit and period. The evaluation of physical vulnerability and risk of buildings is the main purpose of this chapter. Nevertheless, it is shown the necessity of considering not only the expected physical damage but also the social fragility and the lack of resilience of the exposed community, that is, a holistic evaluation of risk aiming at guiding decision making. Both the vulnerability index and capacity spectrum methods for the evaluation of the physical risk are discussed herein. Both provide good results for the considered case study the urban area of Barcelona, Spain. Both methods show how a city, located in a low to moderate hazard region, which has paid no attention to the seismic performance of their buildings, has buildings with a high seismic vulnerability and a considerable seismic risk
Protocol for soil functionality assessment in vineyards
Protocols used by Resolve partners during the project, to assess soil functionality on degraded aeras and evaluate soil restoration after applying recovering practices
Protocols for soil functionality assessment in vineyards
The purpose of this guideline is to describe the methods used during ReSolVe project for soil functionality assessment, so they can be implemented in similar studies.
A brief introduction first underlines what are the main functions of soil and why maintaining an optimal soil functionality is particularly of major interest in viticulture.
Then the different protocols selected for ReSolVe project and this guideline are presented according to the following classification:
- Part I: assessment of soil physical and chemical features;
- Part II: assessment of soil biological features (ecosystem service provision and providers);
- Part III: assessment of rhizosphere biological features;
- Part IV: assessment of grapevine quantitative and qualitative indicators reflecting soil functionality.
In each part, global objectives of the monitoring are explained (what is it used for, in which cases…) and the parameters to evaluate are listed with their corresponding methodological sheet.
In these sheets, instructions and information are given about:
- Materials needed to perform the sampling and the measurement
- Sampling procedure
- Analysis procedure
- Possible interpretations and conclusions that can be drawn (value and meaning of the results, indication of reference values when existing, potential limit of the protocol)
- Bibliographic references related to the method described
- Additional helpful information where appropriate (ex: template of sampling sheet
A mechanical method for the vulnerability assessment of masonry buildings
This paper discusses a mechanical model for the vulnerability assessment of masonry buildings that takes into
account the uncertainties inherent to the structural parameters and the limit states. At first a bilinear model for
the capacity spectrum for masonry buildings is derived as an analytical function of a few number of geometrical
and mechanical parameters. Applying a suitable procedure for the uncertainty propagation, the statistical
moments of the structural capacity is obtained as a function of the statistical moments of the input parameters,
showing the role of each in the results. Using the capacity spectrum method formulated in the so called N2
procedure, vulnerability analysis is carried out with respect to a certain number of random limit states which
depend, in turn, on the building parameters. Fragility curves are derived taking into account the uncertainties of
each quantity involved
Joint scaling laws in functional and evolutionary categories in prokaryotic genomes
We propose and study a class-expansion/innovation/loss model of genome
evolution taking into account biological roles of genes and their constituent
domains. In our model numbers of genes in different functional categories are
coupled to each other. For example, an increase in the number of metabolic
enzymes in a genome is usually accompanied by addition of new transcription
factors regulating these enzymes. Such coupling can be thought of as a
proportional "recipe" for genome composition of the type "a spoonful of sugar
for each egg yolk". The model jointly reproduces two known empirical laws: the
distribution of family sizes and the nonlinear scaling of the number of genes
in certain functional categories (e.g. transcription factors) with genome size.
In addition, it allows us to derive a novel relation between the exponents
characterising these two scaling laws, establishing a direct quantitative
connection between evolutionary and functional categories. It predicts that
functional categories that grow faster-than-linearly with genome size to be
characterised by flatter-than-average family size distributions. This relation
is confirmed by our bioinformatics analysis of prokaryotic genomes. This proves
that the joint quantitative trends of functional and evolutionary classes can
be understood in terms of evolutionary growth with proportional recipes.Comment: 39 pages, 21 figure
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